Acura RLX Sport Hybrid (2014)



Acura RLX Sport Hybrid

In early 2013, Acura introduced the 310-horsepower RLX luxury-performance sedan with a new 3.5-liter all-aluminum, direct-injected VTEC V-6 engine, a number of signature Acura technologies and Precision All-Wheel Steer™ (P-AWS™), creating a new value proposition with superior cabin space and outstanding driving performance in Acura's flagship sedan. Acura is again raising the bar with the introduction of the Acura RLX Sport Hybrid SH-AWD™, the most powerful and technologically advanced Acura sedan yet and the first to apply Acura's groundbreaking new three-motor Sport Hybrid system with electric SH-AWD (Sport Hybrid SH-AWD).

With a direct-injected V-6 engine and an all-new 7-speed dual-clutch transmission (DCT) with built-in motor-generator powering the front wheels, and two rear electric motors powering the rear wheels, the 377-horsepower RLX combines V8-like performance and 4-cylinder-like fuel efficiency along with exhilarating "on the rails" handling performance, courtesy of its electrically-powered torque-vectoring all-wheel drive system.

The Acura RLX Sport Hybrid further elevates Acura's commitment to create "the synergy between man and machine" -vehicles that truly respond to the will of the driver - and deliver new levels of technology-enhanced performance, comfort and convenience. Like the RLX with P-AWS™, the RLX Sport Hybrid delivers class-leading interior space and comfort and a host of signature Acura technologies, including Jewel Eye™ LED headlights, Lane Keeping Assist, Adaptive Cruise Control with Low-Speed Follow, and the next generation AcuraLink® connected car system. In addition, the RLX Sport Hybrid applies new Acura technologies including:

  • Head-Up Display - this first-ever Acura head-up display projects key information at a glance on the lower portion of the windshield directly in front of the driver. Display modes include SH-AWD system operation, tachometer, turn-by-turn navigation, compass, ACC/LKAS along with vehicle speed.
  • Electronic Gear Selector - the RLX also is the first Acura to feature Acura's new fully electronic push-button gear selector, eliminating the conventional shift-lever and allowing the driver to select drive mode (Drive, Neutral, Park) at the push of a button. In addition, the system will automatically engage the Electronic Parking Brake when the driver selects park and unbuckles his/her seatbelt.
  • Reactive Force Pedal - in place if a conventional spring mechanism providing force against the driver's push on the gas pedal, the RLX Sport Hybrid utilizes an electric mechanism that dynamically varies pedal force to assist the driver in applying the optimum amount of engine power in any driving condition. For example, when climbing a snowy hill, the Reactive Force Pedal will increase pedal force to discourage the driver from applying too much engine torque that may lead to unwanted tire slip.

Using smart packaging, advanced aerodynamic design and lightweight body construction, along with fuel-saving hybrid powertrain technology, the RLX Sport Hybrid has the most spacious five-passenger seating in its class along with a top-class EPA fuel-economy rating of 28/32/30 mpg (city/highway/combined).

With a longer wheelbase and wider greenhouse than competing mid-luxury sedans, the new Acura RLX Sport Hybrid SH-AWD delivers full-size interior space in a nimbler, mid-size luxury sedan package. The RLX boasts the longest rear-seat legroom (38.8 inches), and best front (59.6 inches) and rear (57.0 inches) shoulder room in the mid-luxury class. The RLX advanced body design makes extensive use of high-strength steel and aluminum, further aiding its outstanding fuel efficiency, straight-line performance, and superior handling agility.

The new RLX Sport Hybrid SH-AWD offers an incredible array of advanced safety, driver-assistive and information and media technologies, including the standard next-generation AcuraLink™ connected car system and Multi-Angle Rearview Camera; along with available Lane Keeping Assist System (LKAS), Adaptive Cruise Control with Low-Speed Follow and Blind Spot Information (BSI) system. Safety systems available on the RLX Sport Hybrid include technologies such as Collision Mitigation Brake System (CMBS), Forward Collision Warning (FCW) and Lane Departure Warning (LDW).

Utilizing Acura's next-generation Advanced Compatibility Engineering™ (ACE™) body structure, along with seven airbags (including a driver's knee airbag), the RLX Sport Hybrid SH-AWD is anticipated to earn top-level safety ratings, including a 5-star NCAP Overall Vehicle Score and an IIHS "TOP SAFETY PICK+" rating, including a GOOD rating in the IIHS small overlap front crash test.

The RLX Sport Hybrid also offers intuitive technology that reduces stress and simplifies the driving and ownership experience - with features such as Electronic Parking Brake with Automatic Brake Hold, a capless refueling system, Smart Entry/Smart Start keyless access system, easy-to-use and customize dual touch screens, "tensionless" e-pretension front seatbelts, and available rain-sensing windshield wipers, among others.

THE SYNERGY BETWEEN MAN AND MACHINE

As the foundation of Acura's product direction, the Synergy Between Man and Machine is the intelligent pairing of useful technologies and luxury features with the idea of creating vehicles that truly respond to the will of the driver. The focus is not on one specific technology, but on the driving experience Acura vehicles provide to the customer. From its sophisticated exterior and interior design, to its balance of performance, low emission and the top-class fuel economy ratings, and advanced and intuitive technology, the RLX Sport Hybrid is designed to exceed the expectations of Acura clients.

MARKET POSITIONING

The Acura RLX Sport Hybrid SH-AWD enters the mid-luxury segment competing against hybrid and/or all-wheel-drive versions of Audi A6, BMW 5-Series, Infiniti Q50, Lexus GS, and Mercedes-Benz E-Class. The RLX is equipped to meet these established competitors, thanks to improvements in virtually every area of its design, performance, technology, luxury and safety features.

POWERTRAIN

The 2014 RLX Sport Hybrid's all-new three-motor hybrid powertrain combines the power of a conventional V-8 engine with 4-cylinder-like fuel efficiency and the performance-enhancing capabilities of torque-vectoring all-wheel drive.

The RLX Sport Hybrid shares it basic engine architecture with the two-wheel-drive RLX with P-AWS. The 3.5-liter, 310-horsepower, 24-valve direct-injected SOHC V-6 engine with i-VTEC® and VCM™ adds an idle-stop feature to further maximize fuel efficiency, and revised cam timing to smooth engine restart after idle stop. Peak torque to the front wheels is rated at 273 lb.-ft. at 4,700 rpm (versus 272 lb.-ft. at 4,500 rpm in the RLX with P-AWS).

An all-new advanced 7-speed dual-clutch transmission (DCT) is standard on the Sport Hybrid—a first for Acura. Unlike a conventional automatic transmission, the DCT offers ultra-quick gear changes and eliminates the need for a torque converter, which significantly improves efficiency. It can operate in fully automatic mode, or can be shifted manually via steering wheel-mounted paddle shifters.

The RLX Sport Hybrid SH-AWD uses three electric motors: a single 35-kilowatt (47 hp) motor that is integrated with the 7-speed Dual Clutch Transmission supplements the V-6 engine in driving the front wheels, and a rear-mounted Twin Motor Unit (TMU) containing two 27-kilowatt (36 hp) motors that dynamically distribute electric-motor torque to the rear wheels. Both the front and rear motors capture kinetic energy during vehicle deceleration and braking and convert it to electricity to supply the Intelligent Power Unit's 72-cell, 1.3-kWh lithium-ion battery pack, located behind the rear seatback. Together, the 310-horsepower V-6 engine and three electric motors produce a total system output of 377 horsepower and 377 lb.-ft. of torque—the most ever in a production Acura.

The front motor is integrated with the 7-speed DCT and is connected to the driveshaft via a clutch. The motor accomplishes three tasks: (1) It supplements the V-6 engine in driving the front wheels when additional power is required, such as in a passing situation; (2) provides regenerative braking to the front wheels; (3) converts engine power to electricity to supplement regenerative braking in recharging the lithium-ion batteries.

Acura's mechanically-based Super Handling All-Wheel Drive (SH-AWD) made its debut on the RL luxury sedan in 2005, and has since been used on a range of Acura models in several iterations. In the RLX Sport Hybrid, SH-AWD operates independent of the gasoline engine. Drawing power from the lithium-ion battery pack, the Twin Motor Unit's two electric motors deliver torque directly to the rear wheels, thereby eliminating the weight and energy losses associated with a conventional driveshaft and differential mechanism.

When cornering, the RLX Sport Hybrid delivers more torque to the outside rear wheel, much like mechanical SH-AWD, but with more available torque at low engine speeds. Sport Hybrid SH-AWD can also simultaneously apply brake torque to the inside rear wheel during cornering to further enhance cornering control. In addition, since it doesn't rely on engine torque, electric SH-AWD can create a larger torque difference between the left and right rear wheels, even during small throttle applications, at low engine speeds or even during deceleration (such as when lifting throttle mid-corner). This substantially magnifies the positive handling benefits of SH-AWD across a much wider range of driving conditions.

Engine Architecture

The RLX Sport Hybrid 3.5-liter VTEC® V-6 has a smooth-firing 60-degree V-angle and compact overall dimensions. The V-6 has a die-cast lightweight aluminum alloy block with cast-in-place iron cylinder liners. The first ever application of direct injection in an Acura vehicle combines with i-VTEC and Variable Cylinder Management (VCM) to give the RLX a potent blend of power and fuel efficiency.

The aluminum-alloy 24-valve engine produces 310 horsepower at 6,500 and generates 273 lb.-ft. of torque at 4,700 rpm. Torque is markedly improved vs. RL in the lower ranges, where the engine typically operates. Along with the increased horsepower, the updated V-6 also contributes to increased fuel efficiency, due in part to internal friction reduction features, including an oil-ring ion-plating treatment, and plateau honing. A new tumble-type intake port design improves combustion efficiency.

Engine Block and Crankshaft

With its 60-degree V-angle, the V-6 engine is inherently smooth and has compact overall dimensions that allow efficient packaging within the vehicle. The V-6 has a die-cast lightweight aluminum alloy block with cast-in-place iron cylinder liners. Made with a centrifugal spin-casting process, the thin-wall liners are high in strength and low in porosity. The block incorporates a deep-skirt design with four bolts per bearing cap for rigid crankshaft support and minimized noise and vibration. The 3.5L V-6 uses a high-strength steel crankshaft for minimum weight.

A new cooling control spacer positioned in the water jacket surrounding the cylinders helps to maintain consistent operating temperature. Plateau honing of the cylinder lining further lowers the friction level between the pistons and the cylinders by creating an ultra-smooth surface. This two-stage machining process uses two grinding processes instead of the more conventional single honing process. Plateau honing also enhances the long-term wear characteristics of the engine.

Pistons/Connecting Rods

Designed with special "cavity-shaped" crowns, the pistons help maintain stable combustion and contribute to stratified-charge combustion. Ion-plated piston rings help reduce friction for greater operating efficiency. The compression ratio is 11.5:1. Heavy-duty steel connecting rods are forged in one piece and then the crankshaft connecting rods are "crack separated" to create a lighter and stronger rod with an optimally fitted bearing cap.

Cylinder Heads/ Valvetrain

Like other Acura V-6 powerplants, the RLX Sport Hybrid engine's 4-valve cylinder heads are a single-overhead-camshaft design, with the cams driven by the crankshaft via an automatically tensioned toothed belt. Made of low-pressure cast, low-porosity aluminum, each cylinder head incorporates a new "tumble port" design that improves combustion efficiency by creating a more homogeneous fuel-air mixture. An integrated exhaust manifold cast into each cylinder head reduces parts count, saves weight, improves flow and optimizes the location of the close-coupled catalyst.

i-VTEC Valve Control System

The RLX Sport Hybrid V-6 engine combines Variable Cylinder Management (VCM) with Variable Valve Timing and Lift Electronic Control (VTEC), which changes the lift profile, timing and lift duration of the intake valves. A switching mechanism allows each cylinder to operate with low-rpm valve lift and duration or high-rpm lift and duration. The rear cylinder bank's valve gear can also leave all intake and exhaust valves closed to maximize fuel efficiency during cylinder deactivation.

The "intelligent" portion of the system is its ability to vary valve operation based on the driving situation and engine rpm. At low rpm, the VTEC intake valve timing and lift are optimized (low lift, short duration) for increased torque, which allows a wide range of 3-cylinder operation. As engine rpm builds past 5,000 rpm, the VTEC system transitions to a high-lift, long-duration intake cam profile for superior high-rpm engine power.

Variable Cylinder Management ™ (VCM™)

The RLX Sport Hybrid engine employs Acura's Variable Cylinder Management (VCM) cylinder deactivation technology. The VTEC system combines with Active Control engine Mounts (ACM) to allow the VCM system to operate with three cylinders in a wide range of situations to maximize fuel efficiency and lower emissions. When greater power is needed, the system switches seamlessly to 6-cylinder operation. With the strong power output of the Direct Injection RLX engine, a 4-cylinder operating mode is not needed.

During startup, aggressive acceleration, or when climbing hills - any time high power output is required - the engine operates on all six cylinders. During moderate-speed cruising and at low or moderate engine loads, the system operates just the front bank of three cylinders.

The VCM system can tailor the working displacement of the engine to match the driving requirements from moment to moment. Since the system automatically closes both the intake and exhaust valves of the cylinders that are not used, pumping losses associated with intake and exhaust are eliminated and fuel efficiency gets a further boost. The system combines maximum performance and maximum fuel efficiency - two characteristics that don't typically coexist in conventional engines.

VCM deactivates specific cylinders by using the i-VTEC (intelligent Variable Valve-Timing and Lift Electronic Control) system to close the intake and exhaust valves while the Power Control Module (PCM) simultaneously cuts fuel to those cylinders. The spark plugs continue to fire in inactive cylinders to minimize plug temperature loss and prevent fouling induced from incomplete combustion during cylinder re-activation.

The system is electronically controlled, and uses special integrated spool valves in the cylinder heads. Based on commands from the system's electronic control unit, the spool valves selectively direct oil pressure to the rocker arms for specific cylinders. This oil pressure in turn drives synchronizing pistons that connect and disconnect the rocker arms.

The VCM system monitors throttle position, vehicle speed, engine speed, automatic-transmission gear selection and other factors to determine the correct cylinder activation scheme for the operating conditions. In addition, the system determines whether engine oil pressure is suitable for VCM switching and whether catalytic-converter temperature will remain in the proper range. Importantly, the drive by wire control is able to finely match torques in 6-cylinder and 3-cylinder combustion modes, making the transition between the two virtually unnoticeable.

Direct Injection System

Conventional engines using multi-port fuel injection mix fuel and air before they enter the combustion chamber. With direct injection, fuel is injected directly into each combustion chamber. This allows for better combustion and overall efficiency.

The RLX V-6 engine is the first application of direct injection for an Acura vehicle in the United States. The system features a compact, high-pressure, direct-injection pump that allows both high fuel flow and pulsation suppression, while variable pressure control optimizes injector operation. A multi-hole injector delivers fuel directly into each cylinder (not to the intake port, as in conventional port fuel injection designs).

The multi-hole injectors can create the ideal stoichiometric fuel/air mixture in the cylinders for good emissions control. Theoretically, a stoichiometric mixture has just enough air to completely burn the available fuel.

Based on the operating conditions, the direct-injection system alters its function for best performance. Upon cold engine startup, fuel is injected into the cylinders on the compression stroke. This creates a weak stratified charge effect that improves engine start-up and reduces exhaust emissions before normal operating temperature is reached.

Once the engine is fully warm for maximum power and fuel efficiency, fuel is injected during the intake stroke. This helps create a more homogeneous fuel/air mix in the cylinder that is aided by the high-tumble intake port design. This improves volumetric efficiency, and the cooling effect of the incoming fuel improves anti-knock performance.

Active Control Engine Mounts and Active Sound Control

A new, more powerful 28-volt Active Control Engine Mount system (ACM) is used to minimize the effects of engine vibration as the VCM system switches cylinders on and off. The 28-volt ACM is a key factor in the VCM's broad range of operation in the new RLX. Sensors alert the Electronic Control Unit (ECU) to direct ACM actuators positioned at the front and rear of the engine to cancel engine vibration. In the cabin of the RLX, an Active Sound Control system further reduces low frequency sound relating to the function of the VCM system.

Vibration Reduction Technology

Since the RLX Sport Hybrid's gasoline engine can be shut down during certain driving conditions (idle stop), it incorporates measures to mitigate engine vibration during restarts. Compared to the two-wheel-drive RLX, the RLX Sport Hybrid has unique intake cam profiles that close the intake valves later, effectively lowering the compression ratio at startup to reduce vibration. To further reduce vibration, the electrically actuated hydraulic Active Control Mounts are synchronized with engine start-up. A dual-mass flywheel helps further reduce engine vibration when the gasoline engine is in operation.

Drive-by-Wire Throttle System

The RLX doesn't use a conventional throttle cable, but instead has smart electronics that "connect" the throttle pedal to a throttle valve inside the throttle-body. The result is less underhood clutter and lower weight, as well as quicker and more accurate throttle actuation. Plus, specially programmed "gain" between the throttle pedal and engine offers improved drivability and optimized engine response to suit specific driving conditions.

Acura's Drive-by-Wire throttle system establishes the current driving conditions by monitoring throttle pedal position, throttle valve position, engine rpm and road speed. This information is used to define the throttle control sensitivity that gives the RLX's throttle pedal a predictable and responsive feel that meets driver expectations. There are two different throttle profiles available in the RLX. When the transmission is in "D" (Drive) the drive-by-wire system uses the normal profile. When the Sport mode is engaged by pressing the Sport button located near the shift lever, the system changes the throttle map to enhance response feel.

Direct Ignition and Detonation/Knock Control

The RLX's Power Control Module (PCM) monitors engine functions to determine the best ignition spark timing. An engine block-mounted acoustic detonation/knock sensor "listens" to the engine, and based on this input, the PCM can retard the ignition timing to prevent potentially damaging detonation. The 3.5L V-6 has an ignition coil unit for each cylinder that is positioned above each spark plug's access bore.

Close-Coupled Catalysts and Variable Flow Exhaust System

The exhaust manifolds of the 3.5L V-6 are cast directly into the aluminum cylinder heads to reduce weight, decrease parts count, and create more underhood space. The result of this casting design is that the two primary catalytic converters are positioned much closer to the combustion chambers. High-efficiency next-generation precious metal catalytic converters are mounted directly to the exhaust port of each cylinder head to enable extremely rapid converter "light-off" after the engine starts. A significant weight savings is realized by eliminating traditional exhaust manifolds.

Downstream of the close-coupled catalytic converters, a hydroformed 2-into-1 collector pipe carries exhaust gases to a secondary catalytic converter located under the passenger cabin floorboard. This high-flow secondary catalytic converter has a large inlet and outlet to enhance exhaust flow. To balance the engine's need for quiet operation at low rpm and higher flow at high rpm, the RLX's dual exhaust system incorporates a variable flow rate feature. Pressure-operated exhaust valves in each silencer are closed in normal operation, reducing exhaust noise by as much as 8 dB. When the driver demands more performance from the RLX, rising exhaust gas pressure opens both valves. The additional exhaust flow ads five horsepower to the engine's peak output.

Emissions Control

The 2014 Acura RLX Sport Hybrid utilizes a higher amount of precious metals in its under-floor catalyst to meet CARB LEV III SULEV 30 emissions standards.

A number of advanced technologies are factors in the emissions performance. The unique cylinder head-mounted close-coupled catalytic converters light off more quickly after engine start up, and a 32-bit RISC microprocessor within the powertrain control module (PCM) boosts computing power to improve the precision of spark and fuel delivery.

The RLX's V-6 engine features Programmed Fuel Injection (PGM-FI) that continually adjusts the fuel delivery to yield the best combination of power, low fuel consumption and low emissions. Multiple sensors constantly monitor critical engine operating parameters such as intake air temperature, ambient air pressure, throttle position, intake airflow volume, intake manifold pressure, coolant temperature, exhaust-to-air ratios, as well as the position of the crankshaft and the camshafts.

To further improve emissions compliance, the 3.5L V-6 makes use of an after-cat design exhaust gas recirculation (EGR) system that allows cleaner, cooler EGR gas to be fed back into the intake system. An EGR system, especially one that delivers a cleaner/cooler charge, reduces pumping loss for better fuel efficiency.

One-Touch Start System

To ensure consistent starting, the RLX has a one-touch start system that maintains starter engagement until the engine starts. Should the driver release the Start button before the engine starts, the system will start the vehicle. Simply push the Start button (with the fob in the vehicle) and the engine will automatically start up.

Noise & Vibration Control

With its 60-degree V-angle and compact, rigid and lightweight die-cast aluminum cylinder block assembly, the 3.5L V-6 powerplant is exceptionally smooth during operation. Other factors that help reduce engine noise and vibration are a rigid forged-steel crankshaft, die-cast accessory mounts, and a stiff cast-aluminum oil pan that reduces cylinder block flex.

Idle Stop Feature

Idle stop stops cylinder combustion and cylinder activation, eliminating fuel use when the vehicle is stopped, such as at traffic light or in heavy traffic conditions. The engine is restarted by the 35-kilowatt front motor-generator using energy from the lithium ion hybrid battery pack. Unlike some competing systems, the engine restart is extremely smooth and refined, practically undetectable to the vehicle's occupants.

7-Speed Dual-Clutch Transmission (DCT)

To maximize performance and fuel efficiency, the RLX Sport Hybrid has a standard 7-Speed Dual-Clutch Transmission (DCT). In the 7-speed DCT, one clutch controls the odd gears while the other clutch controls the even gears. This arrangement allows gear changes with a much smaller interruption in power to the wheels, resulting in millisecond-quick shifts. Compared to a conventional manual transmission, the operation of the clutches and shifting mechanisms are electronically controlled, eliminating the need for a clutch pedal or shift lever. Compared to a conventional automatic, the torque converter and its mechanical inefficiencies are also eliminated. The DCT transmission in the RLX Sport Hybrid also features a 17-percent wider ratio range than the 6-speed automatic transmission in the RLX with P-AWS.

Electronic Gear Selector

In the RLX Sport Hybrid, a conventional console-mounted shift lever is replaced with an all-new Electronic Gear Selector fully electronic, shift-by-wire gear selector. Park, Neutral and Drive are selected with the push of a button. Reverse is selected by pulling back a dedicated switch. Indicator lights near the buttons indicate the mode selected. As an added safety feature, if the vehicle is brought to a stop in Drive, the system will automatically select Park if the driver's seatbelt is unbuckled and the driver's door is opened.

Transmission Modes

When in Drive mode, the 7-speed dual-clutch transmission can be controlled steering wheel-mounted paddle shifters. While traveling up or down hills, Grade Logic Control alters the transmission's shift schedule to reduce shift frequency and improve speed control. A shift map in the transmission computer continually measures throttle position, vehicle speed and acceleration/deceleration, and then determines when the vehicle is on a hill. The shift schedule is then adjusted to hold the transmission in lower gears to boost climbing power or to provide engine braking when traveling downhill.

Shift Hold Control keeps the transmission in its current (lower) gear ratio when aggressive driving is detected, as in the case of decelerating at a corner entry. Shift Hold Control leaves the chassis undisturbed by excess shifting and ensures that power will be immediately available (without a downshift) at the corner exit.

The RLX Sport Hybrid features Sport and Normal modes. A selector button located on the center console allows the driver to toggle between the two operating modes. Normal mode is aimed at overall energy efficiency. Sport mode, by contrast, puts greater emphasis on the driving experience, delivering a more responsive and direct feel. Sport mode offers more aggressive and sporty shift mapping, engine rpm "blips" on downshifts, while VCM and idle stop functions are cancelled. All of the transmission logic systems work together to automatically alter shift timing based on driving conditions.

Temporary Manual Operation in "Drive"

Whether in Drive or Sport mode, special transmission logic programming allows the use of the steering-wheel-mounted paddle shifters. When the driver operates the steering wheel-mounted paddle shifters while in Drive, the transmission responds to the driver's shift command and then returns to its normal fully automatic mode if further paddle shift inputs are not made within a given time. This special logic makes it easy for the driver to command a quick downshift without leaving the comfort of Drive mode. When in Sport mode, use of the paddle shifters puts the transmission into full manual mode that remains until another mode of operation is selected.

Manual Mode

By pressing the "Sport" button located near the gear selector button, Sport mode is engaged. This mode offers automatic operation with more aggressive shift mapping. A pull on the racing-inspired paddle shifters (mounted on the steering wheel) places the transmission in fully manual mode. A digital display in the instrument cluster indicates which gear the transmission is in. The system reverts to normal fully automatic mode if further paddle shift inputs are not made within a given time.

Sport Hybrid Super Handling All-Wheel Drive (SH-AWD)

The RLX Sport Hybrid is the first production vehicle to employ an electric version of Super Handling All-Wheel Drive (SH-AWD). Previous mechanical versions of SH-AWD had the ability to vary the amount of power sent to the rear axle, and to also vary rear power distribution between the left and right rear wheels via a longitudinally mounted drive shaft and rear differential with twin electronically controlled clutch packs.

In the RLX Sport Hybrid, the driveshaft and rear differential of a conventional all-wheel drive system is eliminated, replaced by twin 27-kilowatt (36 hp) electric motors that independently drive the left and right rear wheels. Each motor can also capture regenerative braking energy and apply negative (regenerative braking) torque to further enhance cornering capability.

Independent distribution of torque to all four wheels is a key feature of SH-AWD and its ability to enhance both dynamic handling and all-weather traction. When cornering, more positive (drive) torque is applied to the outside rear wheel, while negative (regenerative braking) torque can be applied to the inside rear wheel. This torque differential creates a yaw moment, producing sharper turn-in, more linear cornering, enhanced traceability and improved steering response with reduced understeer tendencies. In addition, since the system doesn't rely on the gasoline engine for torque, electric SH-AWD can create a larger torque difference between the left and right rear wheels, even during small throttle applications, at low engine speeds, or even during deceleration (such as lifting throttle mid-corner). This substantially magnifies the positive handling benefits of SH-AWD across a much wider range of driving conditions.

Power Drive Unit (PDU)

The Power Drive Unit, packaged in the center of the vehicle beneath the center console, dictates the power management strategy of the Sport Hybrid SH-AWD system, including motor power and battery recharge.

Intelligent Power Unit (IPU)

The Intelligent Power Unit is positioned above the Twin Motor Unit, behind the rear seatback. The IPU contains the hybrid system's lithium-ion battery, 12-volt DC/DC converter, junction board, and Electronic Control Units (ECU) for the motors and the battery. The IPU is air-cooled via an integrated fan unit that draws air from inside the vehicle cabin via an intake duct located beneath the rear seats.

1.3-kWh Lithium-Ion Battery

The RLX Sport Hybrid's advanced 72-cell lithium-ion battery has 29 percent greater power density and 5 percent greater energy density compared to the lithium-ion battery in the ILX hybrid.

Front Electric Motor

A single 35-kilowatt (47 hp) electric motor is integrated with the 7-speed DCT. The motor's operating temperature is optimized by a temperature-controlled flow of Automatic Transmission Fluid (ATF) through the motor housing. By tightly controlling the motor temperature, the motor's torque output (both drive and regeneration) can be improved up to 100 percent.

Twin Motor Unit (TMU)

The RLX Sport Hybrid's Twin Motor Unit (TMU) is located in between the rear wheels, where a differential on an all-wheel-drive vehicle is typically mounted. Inside its die-cast aluminum housing are two electric motors positioned back-to-back. Each 27-kilowatt (36-horsepower) motor powers a single rear wheel and can also apply negative torque to the same wheel. A clutch allows each motor to be decoupled from its wheel in certain operating situations to improve efficiency.

Electrically Powered Air Conditioning Compressor

Since the RLX Sport Hybrid engine has an idle-stop feature, it is equipped with an electrically powered air conditioning compressor. This allows continuous air conditioning operation even when the gasoline engine is shut off.

Hybrid System Safety

To maximize passenger safety, the hybrid system components are positioned in well-protected areas of the vehicle. In the event of a collision that triggers the airbags, an automatic high-voltage circuit interrupt in the Intelligent Power Unit cuts power to the hybrid system.

100,000 Mile Tune-up Intervals

The RLX's 3.5L V-6 requires no scheduled maintenance for 100,000+/- miles or more, other than periodic inspections and normal fluid and filter replacements. The first tune-up includes water pump inspection, valve adjustment, replacement of the camshaft timing belt, and the installation of new spark plugs.

Maintenance Minder™ System

To eliminate unnecessary service stops while ensuring that the vehicle is properly maintained, the RLX Sport Hybrid has a Maintenance Minder™ system that continually monitors the vehicle's operating condition. When maintenance is required, the driver is alerted via a message on the Multi-Information Display (MID).

The Maintenance Minder™ system monitors operating conditions such as oil and coolant temperature along with engine speed to determine the proper service intervals. Depending on operating conditions, oil change intervals can be extended to a maximum of 10,000 miles, potentially sparing the owner considerable expenditures and inconvenience over the life of the vehicle. The owner-resettable system monitors all normal service parts and systems, including oil and filter, tire rotation, air-cleaner, automatic transmission fluid, spark plugs, timing belt, coolant and more. To avoid driver distraction while the vehicle is being operated, maintenance alerts are presented on the MID when the ignition is first turned on.

Design Concept

Bristling with technological advances in lighting, aerodynamics and construction, the 2014 RLX Sport Hybrid SH-AWD body has the technology to match its athletic and sophisticated design. Lightweight and aerodynamic, the body provides outstanding collision protection, confidence-inspiring high-speed stability, and exceptional fuel efficiency.

The RLX's dynamic body design combines a sleek overall shape, "aero-fused" cabin silhouette, and close tolerances for the wheel wells and body-panel gaps for a high degree of elegance and aerodynamics. The styling begins with a dynamic front-end featuring the RLX's signature Jewel Eye™ LED headlights, a substantial presence that imparts a look of power and confidence, while also proving highly aerodynamically efficient, providing powerful down the road illumination and even encompassing advanced pedestrian safety features.

Decisive character lines start alongside the hood, sweep over the front wheel arches, and then along the body sides. The body sides feature decisive character lines that subtly rise along the lower body sides, dramatically changing the light reflections and creating an especially dynamic visual signature for the RLX.

This athletic and sophisticated look is complemented by a flowing, aerodynamically sleek cabin design. Referred to by Acura designers as an "aero fused shape," the cabin is wide but also extremely aerodynamic, allowing both a roomy interior and a quiet ride quality as air slips smoothly over the cabin's flush-mounted available acoustic glass and other drag- and turbulence-reducing design details.

The wheel-arch hems use a much smaller gap to the tire than on the RL - and also a much smaller gap than is typical for the segment. This results in a more poised, integrated and finished look for the RLX side profile. The wheel-arch hems are also beautifully finished, adding to the sense of quality. Likewise, the hood, door and trunk-panel gaps are carefully controlled, with the aggregate effect that the RLX is immensely well crafted.

Beneath the vehicle is a sophisticated series of aerodynamic aids that further smooth airflow. These include an engine undercover, left and right floor covers, left and right mid under covers, and a rear under cover.

The rear of the RLX body is also dynamic, and here the cabin is noticeably wider than either of the outgoing RL or the RLX's primary competitors, lending a look of soliditydue to the wider overall body and track widths.

Additional model-exclusive design cues for the RLX Sport Hybrid include a dark chrome-plated grill insert and redesigned lower front bumper fascia with integrated LED fog lights and turn signal indicators. The RLX Sport Hybrid has exclusive 19-inch, 10-spoke alloy wheels and "Hybrid" badging on the front fender. Also, SH-AWD badging replaces the P-AWS badge on the right rear portion of the trunk lid.

Seven different exterior colors, including four metallic and three pearl, are designed to complement the exterior shape and the way light defines it.

The Acura RLX Sport Hybrid utilizes numerous aluminum components to lower the overall vehicle mass by 76 pounds, which helps to improve acceleration, steering and handling response, road-holding, braking performance, fuel efficiency, emissions, and crash safety. Aluminum components include the front and rear bumper beams, front fenders, hood, steering column mounting beam, floor pan, and door skins.

Exterior Dimensions

The 2014 RLX Sport Hybrid is larger than the previous RL model in several key exterior dimensions, including width, wheelbase, and front and rear track. In overall length, the RLX measures 196.1 inches - just 0.2 inches longer than the previous model; however its wheelbase, at 112.2 inches, is a full two inches longer, providing more rear passenger room and improved the ride quality.

At 74.4 inches wide, the RLX is a substantial 1.8 inches wider than the previous model, contributing to the RLX's more spacious interior - now with an impressive 36.4 inches between seating rows - its more confident visual presence, and improved handling stability.

At 57.7 inches high, the RLX is just 0.4 inches taller than the model it replaces.

Among its competitive set, the new RLX is longer and wider than the Audi A6, BMW 5 Series, Lexus GS series, and Mercedes-Benz E-Class.

Waiting Status

When parked and locked, the folding exterior mirrors retract, the security alarm system is armed, and the RLX goes into standby mode, waiting for its owner to return. Then when the driver (in possession of the key fob) approaches the vehicle, it unlocks the driver's door (or all doors if so programmed). When the driver opens the door to be seated, the RLX adjusts the seat and steering column to the preset positions, actives the instrumentation and sets the other features such as climate-control and audio-system presents to match the driver.

Body Rigidity

Static and dynamic rigidity and rear lateral stiffness are all improved versus the RL and even compared to the RL-X with P-AWS. Static bending rigidity is up 53 percent and torsional rigidity is up 47 percent compared to the previous RL model (1 percent up from the RLX with P-AWS). In addition, rear lateral stiffness and the torsional rigidity of the rear upper damper mounting points are up 107 percent and 63 percent, respectively, compared to the previous RL (and up 25 percent and 12 percent when compared to the RLX with P-AWS).

High-Strength Steel

To increase stiffness and rigidity in key areas without increasing weight, 55 percent of the RLX body is made from high-strength steel, including the strategic use of ultra-high strength "hot stamped" 1500Mpa steel.

Aluminum Body Components

Extensive use of aluminum in key areas saves 76.1 pounds compared to traditional all-steel construction, providing high strength with light weight that directly benefits ride, handling, fuel efficiency, emissions reductions and safety. The biggest weight savings from a single component comes from the use of an aluminum hood, which saves 19.6 pounds compared to a steel hood. Aluminum body components include:

  • Hood
  • Front bumper beam
  • Front fenders
  • Floor tunnel bar
  • Rear bumper beam
  • Steering-column hangar beam
  • Front door skin
  • Rear door skin

Aluminum Hybrid Construction Door

The RLX doors are a hybrid construction utilizing aluminum outer panels for lighter weight and steel inner panels for stiffness and crash safety performance. Together, they provide for increased stiffness with a weight reduction of 24.3 pounds compared to all-steel doors.

The front doors are constructed of four parts, while the rear doors are constructed of five parts. The steel inner panel uses a special high-corrosion-protection zinc, aluminum and magnesium plating - 11 percent aluminum, 3 percent magnesium and 86 percent zinc - to assure that electrolytic corrosion does not occur between the two metals. This plating gives the steel inner panel 10 times the resistance of traditional zinc galvanized plating.

The outer aluminum skin and steel inside panels are joined with an Acura-first "curl forming" process for high-strength and durability.

Class-Leading Aerodynamics

More than 800 wind-tunnel tests were conducted to improve vehicle aerodynamics values. As a result, the new RLX will have class-leading lower coefficient of lift (CL) and lower coefficient of drag (Cd).

Sound Insulation

Engineers paid particular attention to reducing interior noise, an effort that extends to literally every aspect of the vehicle's design and engineering - from aerodynamics and powertrain engineering to insulators and the selection of finishing materials - all play a part in the RLX's improved interior quietness.

To achieve a premium level of interior quietness, the RLX receives an unprecedented amount of acoustic material in key areas. The list includes:

  • Carpet back surface
  • Inside front/rear door lining
  • Inside A-pillars
  • Inside C-pillars
  • Roof area behind moonroof opening
  • Floor sills
  • Inside trunk lid
  • Rear deck
  • Rear bulkhead
  • Rear wheel wells

To mitigate additional sound from the hybrid drive motors, the RLX Sport Hybrid features additional application of sound deadening materials in rear passenger floor and trunk floor insulators.

Acoustic Door Glass

The RLX Sport Hybrid uses laminated, sound-insulating acoustic glass for all door glass, providing an extra measure of wind and road noise attenuation (same as RLX with P-AWS Technology and higher grades). The glass is 4.7mm thick and includes an acoustic membrane that helps attenuate frequencies above 1,600 Hz, resulting in an improvement of up to 14.7 dB over the previous model's 5mm thick tempered door glass.

Jewel Eye™ Headlights

The 2014 RLX Sport Hybrid features Acura Jewel Eye™ LED headlights, which utilize a dual-stacked array of high-intensity LED lamps to deliver outstanding light distribution, and class-leading distant irradiation performance and light characteristics with a wavelength close to the human eye's luminosity curve. With two rows of five "Jewel Eye" lights per headlight, the LED lights provide improved down the road visibility compared to HID and halogen headlights.

On each side of the RLX, the low beams consist of four LED lights, while the innermost high beams utilize a pair of larger LED lights. The daytime running light (DRL) function is shared by the low-beam lenses, with the eight individual lenses clearly and dramatically visible even in bright sunlight. Altogether, they create a dramatic and distinctive appearance with superior lighting capability.

Light distribution

Both the low and separate high beam LED headlights offer outstanding performance in all nighttime driving conditions, including highway, winding roads, intersections, and in inclement weather conditions. The result is that the driver can see further with uniformity, making high-speed nighttime driving easier and less fatiguing.

A summary of LED benefits include:

  • Outstanding light distribution that surpasses competitors
  • Excellent distant illumination performance
  • Clear illumination of the road surface and white lines
  • High visibility of the entire visible color spectrum (white, red, green, blue and yellow) compared to HID and halogen headlights
  • Response time when switching between low and high beam is shortened
  • Light congruity is improved between low and high beams

When the lights are off, sunlight enters the display through the top of the lens, reflects off the rear reflector and then forward and through the lens again. As a result when lighting is off, the array still appears to be shining.

LED Taillights

The RLX Sport Hybrid taillights utilize periphery LED illumination that is both effective and highly distinctive. The taillight array consists of two semi-circular LED rings sweeping across the rear fender edges and the sides of the trunk lid. The light path combines functions of both the taillights and the side marker lights in one array. This LED array matches the "Jewel Eye" headlights for elegance and clearly distinguishes the RLX from every other vehicle on the road - even at a distance and especially at night. It also compliments the RLX body design.

LED taillight components include the LED assembly, a housing/reflector and inner and outer lenses. Uniform illumination is provided by a combination of light diffusion and the specially grained finish of both an inner lens and a reflecting surface. Inside the periphery LED taillight array is a separate lighting array consisting of the stoplights and turn signals. Backup lights are located on the trunk lid, inside the perimeter taillight array.

LED Fog Lights

LED fog lights present a smaller face than traditional fog lights, making them less susceptible to damage, while offering longer life, lower energy draw and more desirable color.

One-Touch Turn Signals

The RLX's one-touch turn signals provide increased convenience for the driver when making routine lane changes. With the one-touch turn signal system, a quick movement of the turn-signal lever (between 0.4 sec. and 1 sec.) provides three blinks of the turn signals - an ideal scenario for changing lanes. Holding the lever for 1 sec. or longer (past the "click point") provides continuous blinking, such as for signaling a turn or exiting a thoroughfare.

Retracting Mirrors

At the driver's preference, the RLX's door mirrors on some grades can be configured to automatically retract when the doors are locked, and then automatically extend when the doors are unlocked. This automatic mirror retract/extend function helps safeguard the mirrors when the RLX is parked, while also creating a higher-quality experience for the driver by eliminating the need to remember to manually retract or extend the mirrors.

The mirrors automatically retract or extend in two ways: 1) simply press the lock/unlock button on the remote key fob; or 2) press the lock button on the door handle.

The mirrors can also be retracted and extended by using the mirror switch on the driver's door panel. These functions can be customized through the MID on the instrument panel.

Expanded View Driver's Mirror

The 2014 RLX's Expanded View Driver's Mirror is integrated into the driver's side mirror. Standard equipment on all trim levels, the mirror increases the driver's field of vision by 6.5-degrees to provide a better view of objects that would otherwise be hidden in the vehicle's blind spot. This allows the driver to better recognize vehicles that are in their blind zone.

The major part of the mirror is flat and provides 15.1-degrees of visibility. Adding the 6.5-degrees of the Expanded View Driver's Mirror yields 21.6-degrees of visibility. In addition, the expansion of the view area gradually changes between flat and convex for a more natural user experience.

Intelligent Wipers

Laws in some states require drivers to turn on the headlights when the wipers are operating in the rain. The new RLX helps its driver comply with these laws by automatically illuminating the headlights when the wipers are activated in rainy conditions (with headlight switch in Auto). Operation is shown via an indicator on the instrument panel. If rain is intermittent, the lights stay on for a predetermined interval before automatically turning off again.

Wiper operation is equally advanced for maximum wiping area, better wiping quality, reduced weight, improved appearance and longer blade life. Details include:

  • Wiper coverage is maximized by controlling the wiper position, including to the outer corners of the windshield.
  • Wiper performance is maximized by adjusting the wiper speed according to road speed and wind pressure.
  • The wiper motor uses a built-in ECU, reducing complexity compared to the RL wiper mechanism. The new RLX wiper motor assembly saves 4.6 pounds in comparison.
  • For better appearance, the wipers are hidden under the hood when not in operation.
  • For extended life of the wiper blades' rubber, the operating system periodically raises the wiper blades from underneath the hood (when not in use) to prevent blade deformation.

Self-Opening Trunk

The RLX trunk has a self-opening feature that fully opens the trunk lid. There are three ways to open the trunk: 1) by pressing the trunk opener switch located on the driver side door panel, 2) with the key fob and 3) with the trunk opener switch located in the middle of the trunk, underneath the trunk lid garnish. This makes it easier for the RLX driver to carry items and open the trunk lid at the same time. In contrast, the previous RL model, the trunk lid would open halfway compared to the RLX's fully open function. The trunk lid closes manually.

Trunk Storage

The RLX Sport Hybrid offers 12.0 cu.-ft. of trunk storage capacity (down from 15.3 cu. ft. in the RLX with P-AWS and 15.1 cu.-ft. in RLX models with Krell Audio and Advance grades). All measurements include the tool kit and the puncture repair kit. A cargo net allows for storage of smaller items in an areas suspended above the cargo floor. Also, beneath the floor panel is a 0.4 cu.-ft. covered storage well.

Multi-Angle Rearview Camera

The RLX's standard multi-angle rearview camera features three viewing angles - Wide view, Normal view and Top Down view. Drivers may select the preferred view according to driving conditions. The rearview camera system also features dynamic guidelines that display the vehicle's backward trajectory according to steering-wheel position. When the steering wheel is straight, a broad 180-degree rearward view can be seen in Wide View, and Normal and Top Down views are also available. However when the steering wheel is turned 90 degrees, only Wide and Normal views are available, and dynamic guidelines curve onscreen to show the path of the vehicle. The result is improved convenience for the driver as the rearward trajectory of the RLX is indicated by the dynamic guidelines.

Rear Wheel Arch Hem

The RLX's sleek exterior design is enhanced by close tolerances between the tires and the wheel arches. Specially designed wheel-arch hems reduce the gap to just 46 mm between the top of the tire and the lower part of the wheel arch, 10.5-mm narrower than that of the previous RL model. As a result, the tires better fill the wheel wells for a greater sense of unity and substance.

Exterior Colors

The 2014 RLX Sport Hybrid is available in seven exterior colors, including four metallic and three pearl colors. All colors have a strong character, offering expressive contrasts that compliment the RLX's body-panel curves and angles, while also exhibiting a smart luxury appearance. The acid-resistant epoxy clear-coat paint is superior to typical clear-coat paints for increased resistance to urban pollutants.

Chassis Concept

The goal behind the RLX Sport Hybrid chassis was to deliver "the synergy between man and machine" or dynamic handling that truly responds to "the will of the driver." This refers to the way in which Acura engineers envisioned the entire package of the RLX responding instantaneously and precisely, with technology used to improve the driver's capability and confidence. The result is a vehicle that, more than any Acura before it, creates a driving experience that performs at the will of the driver.

Sport Mode

A driver-selectable Sport mode further enhances driving dynamics across a wide range of driving situations. When the driver engages the Sport button on the center console, the system adopts more aggressive shift mapping and rear wheel torque-vectoring control. The system also deactivates Idle Stop, Variable Cylinder Management (no 3-cylinder mode) and the Reactive Force Pedal, plus the Active Sound Control system is modified to provide an even sportier driving experience.

Front Aluminum Subframe

The RLX Sport Hybrid has a lightweight and rigid front aluminum front subframe that is specifically designed to support the high performance of the double wishbone, lower double-joint front suspension with Amplitude Reactive Dampers and belt-type Electric Power Steering (EPS) system. Using die cast front corners, the Acura RLX Sport Hybrid's front subframe is also wider across the middle, features wider middle and rear rails, and a wider rear section vs. RL to accommodate the new EPS system. Rigidity is up 82 percent compared to RL.

With its lightweight and rigidity, the new aluminum front subframe contributes to agile and light handling, straight-line stability, higher fuel efficiency, flat cornering and pleasing ride comfort, and smooth and precise steering feel (with reduced torque steer tendencies).

The RLX Sport Hybrid subframe is matched to the Active Control Engine Mount (ACM) system that is engineered specifically for the RLX's higher-output engine and Variable Cylinder Management (VCM) system.

Lower Double-Joint Front Suspension

The RLX Sport Hybrid utilizes the same double-wishbone, lower double-joint front suspension as the RLX with P-AWS, which significantly improves intuitive handling agility, driver confidence and security, and ride sophistication. The system includes a lower double joint with a split lower control arm, optimized kingpin geometry, upper control arm, hydraulic compliance bushing, special dual-stage Amplitude Reactive Dampers made for Acura by ZF-Sachs, and a stabilizer bar that is heat treated for high strength.

Benefits include:

  • Agility - Improved steering feel characteristics including stability, linearity, response and tracing performance
  • Driver Confidence - Increased high speed linearity with reduced torque steer/pulling, shimmy and judder
  • Ride Sophistication - Flat ride with reduced harshness and steering vibration

Multi-Link Rear Suspension

Like the lower double-joint front suspension, the RLX Sport Hybrid's multi-link rear suspension with Amplitude Reactive Dampers provides optimal handling agility, driver confidence and ride sophistication. The multi-link system geometry is optimized for a flat ride during cornering, confident turning capability, and a sophisticated ride in a variety of urban, highway and open road scenarios. The system includes multi-link control arms, control-arm bushings that are optimized for the best blend of NVH isolation and handling precision, Amplitude Reactive Dampers, and a rear stabilizer bar that is hardened with a special shot-peening process.

Amplitude Reactive Dampers

Amplitude Reactive Dampers provide superior ride comfort and handling in all driving conditions. The dampers have two separate damping mechanisms: one that is tuned for maximum efficiency on smoother roads with small inputs; and the other that is tuned to handle large inputs such as rough roads, potholes, and sudden steering and braking action. The result is a vehicle that remains composed and comfortable in a wide range of driving conditions.

The core technology contained within the Amplitude Reactive Dampers is their two separate damping pistons, including a main piston and a second piston. To improve overall ride comfort, when smaller inputs occur during normal driving conditions, only the main piston works to provide the ideal damping characteristics. To improve the RLX's ride and handling during more severe conditions, the second piston operates to provide additional damping force.

The Amplitude Reactive Dampers are a purely mechanical system that does not require electronic controls. Altogether, they provide a much wider range of damping performance than the previous RL.

High-Output Electric Power Steering (EPS)

The RLX Sport Hybrid Electric Power Steering (EPS) system uses a high-power, belt-type electric steering assist. The system increases the torque available to assist the driver in steering the vehicle smoothly, with instantaneous response, direct feel, and improved low-speed agility and high-speed stability.

The variable gear ratio EPS uses a high-output electric assist motor with a belt-drive system. The system is designed and tuned to provide the two most essential characteristics in a high-performance luxury vehicle's steering. These include a smooth initial response (shorter delay) at the start of steering input, and greater linearity response (steering force camber increase) as input is increased. As a result, the RLX's high-output EPS provides agile performance in low-speed driving maneuvers such as at intersections, improved overall accuracy and road feel, and superb high-speed stability.

Rigid Steering Column

The RLX Sport Hybrid steering column is a highly rigid design with an aluminum bracket and resin angular bearing. The resulting stiffness gives maximum driver steering feedback along with minimizing vibration felt in the wheel.

The steering shaft is significantly larger in diameter than the shaft found in the previous RL, and together with the stiff but lightweight aluminum support bracket and angular bearing, yields maximum vibration-damping characteristics for a more luxurious driving experience.

Electrically actuated tilt and telescoping adjustment makes it easy to set the steering wheel to the ideal position for drivers of different sizes.

4-Wheel Disc Brakes with ABS and Brake Assist

RLX Sport Hybrid is equipped with 4-wheel disc brakes with a 4-channel anti-lock braking system (ABS) for confident stops. The front discs measure 12.99 inches in diameter, while the rear discs measure 12.2 inches in diameter.

ABS independently modulates braking power at each wheel to help the driver retain steering control during heavy braking, while Brake Assist recognizes emergency braking situations and almost instantly applies full braking force when appropriate.

The brake pads are a high-friction type for peak stopping performance even under strenuous conditions. The brake calipers are designed to reduce brake drag when not in use, reducing rolling resistance and improving fuel efficiency in the process.

Electric Servo Brakes

The RLX Sport Hybrid's electric servo brake system maximizes regenerative braking capability for improved fuel efficiency. The braking system is fully hydraulic from the master cylinder all the way to the 4-wheel disc brakes, just like a traditional braking system. The key difference is that the braking function is electronically controlled rather than a purely mechanical activation, allowing regenerative braking from the front and rear electric motors to slow the vehicle, rather than the hydraulic friction brakes, under most circumstances. Besides its payoff in efficiency, the system offers excellent feel and feedback for the driver through the brake pedal.

When the driver applies the brake pedal, a signal is sent to the vehicle's Electronic Control Unit (ECU), which determines the appropriate amount of braking force to assign to regenerative braking through the electric drive motor and to the hydraulic friction braking system. In many cases, friction braking is not needed until the vehicle speed drops below 9 mph, as the vehicle slows to a final stop. When the ECU determines that friction braking is needed, the dual hydraulic master cylinder pumps brake fluid through the system. Midway between the master cylinder and the calipers is a separate motorized electronic actuator. This actuator receives an electronic signal, generated in the master cylinder module that precisely defines how the driver has applied the brakes - soft or hard, slow or fast. The actuator then directly apportions hydraulic pressure to the brake calipers at each wheel.

While the RLX with P-AWS uses a 10-inch vacuum booster to assist the driver in applying needed brake pressure, the RLX Sport Hybrid uses an electric servo brake actuator.

Reactive Force Pedal

The RLX Sport Hybrid is the first model to apply the Acura-developed Reactive Force Pedal technology. In Normal mode, the system measures vehicle speed and dynamically varies pedal force to help the driver in applying the optimal amount of throttle for both spirited performance and good fuel economy. In slippery conditions, the system can also help the driver apply the optimal amount of driving force while minimizing wheel slip, utilizing input from the Vehicle Stability Assist system. Further, in the event that the Collision Mitigation Brake System (CMBS) detects that a frontal collision is imminent, the Reactive Force Pedal will push back on the driver's foot even before the CMBS system activates its visual and auditory alerts.

Electric Parking Brake + Automatic Brake Hold

The combination of Electric Parking Brake (EPB) and Automatic Brake Hold are a first for the Acura division. Together, they meaningfully reduce the effort of driving the vehicle, thereby raising overall comfort to a true flagship level.

Electric Parking Brake

The Electric Parking Brake (EPB) on the RLX Sport Hybrid makes using the parking brake easier and more comfortable. Actuating the parking brake is now as simple as pulling a button on the center console. To release the parking brake, the driver simply presses on the accelerator pedal. In addition to being simpler, more convenient and more comfortable to us