HEADLINES

2008 Acura RL - Body

BODY DESIGN & STRUCTURE

The 2008 Acura RL combines its dynamic exterior and interior design with advanced body and chassis engineering. The result is distinctive and appealing styling, together with excellent maneuverability on the road. To ensure that the RL has exceptional dynamic capabilities and driving quality, it is outfitted with a lightweight and highly rigid body structure that makes extensive use of both high-tensile steel and aluminum components, and features 4-wheel independent suspension.

DESIGN CONCEPT

Acura designers wanted to create a taut and athletic shape that conveyed the performance capabilities of the RL without sacrificing comfort and capability.

To create an exhilarating, athletic sedan, the designers targeted superior dynamic performance, superb maneuverability, distinctively appealing styling, and a high level of active safety. The result is a top-flight luxury performance sedan able to compete with the Audi A6, BMW 5 Series, Mercedes-Benz E Class and others.

Design Image

Acura designers set out to give the RL a pronounced sporting persona. To help craft the image, styling cues included the following:

  • Taut, athletic body design with European influence
  • Aerodynamic design with low drag and high stability
  • Low hood line for increased forward visibility and reduced aerodynamic drag
  • Flush side glass for reduced wind noise
  • Short tail for reduced aerodynamic drag and improved maneuverability

Aero Sculpture

The aerodynamic properties of the RL complement the styling, safety, dynamic performance, stability, human factors and other considerations. To achieve this high-performance exterior, the RL designers created a strong wedge shape that begins its "momentum" with the hood, continues it with a forward-mounted windshield, and finishes with a short rear overhang. The aerodynamic cabin has flush side glass for reduced drag and less wind noise. Along with outstanding aerodynamic performance, the RL is designed to look like it moves fast.

Packaging

The packaging goal for the RL was to create a taught body with short overhangs and wide interior dimensions for enhanced comfort and convenience.

Controlling the weight of the RL was important for maximum acceleration, road holding and braking performance — so lightweight materials and weight-saving design were key.

 

2008
Acura
RL

2007
Audi A6  
3.2

2007
BMW
528i

2007
Infiniti
M35x

2007
Lexus
GS 350

2007
Mercedes
E320 4Matic

Drive system

SH-AWD

AWD

AWD

AWD

AWD

AWD

AWD system

Standard

Standard

Optional

Optional

Optitonal

Optional

Length, in.

193.6

193.5

191.1

192.6

190.0

191.2

Width, in.

72.6

79.2

72.7

70.8

71.7

71.7

Height, in.

57.1

57.4

58.3

60.4

56.5

59.0

Wheelbase, in.

110.2

111.9

113.7

114.2

112.2

112.4

Track, Front/Rear, in.

62.0/62.4

63.5/63.7

61.3/62.3

60.2/60.8

60.4/60.6

61.3/61.1

Curb weight, lb.

4,012
(SH-AWD)

4,034
(AWD)

3,704
(AWD)

4,043
(AWD)

3,869
(AWD)

3,955
(AWD)

Weight distribution, %, F/R

58/42

56/44

52/48

55/45

55/45

51/49

BODY STRUCTURE

Light Weight

Producing a lightweight and rigid unit body was essential to making the RL a premium luxury sport sedan. This is because light weight improves every aspect of dynamic performance and fuel economy, and a rigid structure improves ride and handling quality.

Specific RL strategies employed to reduce body mass include:

  • Aluminum hood, front fenders, trunk lid, and trunk lid frame
  • Aluminum front and rear subframes, suspension arms and bumper beams
  • Magnesium cylinder head covers and seat frames
  • Carbon fiber reinforced composite drive shaft

Structural Solidity

The Acura RL was also designed with the goal of creating an automobile body that provides world-class safety. It was engineered to comply with the latest FMVSS 208 occupant crash protection standard and FMVSS301 fuel system integrity standard.

One of the most difficult test modes to achieve is the side collision that models the impact of a RL being struck from the side by an SUV or a pickup truck. To meet these important benchmarks, engineers increased the side section of the frame to comply with new collision regulations (see Safety section for more information). They also chose different material specifications to provide the desired level of stiffness and strength for critical areas, without adding unnecessary weight.

The use of aluminum for the front and rear bumper beams, hood, trunk lid and front fenders saves 40 pounds compared to if made from steel

  • Extremely strong Grade 80 high-tension steel is used for the side sills, under-floor spars, and in the impact-absorbing crumple zones at the front of the side frames
  • Strong high tension Grade 45 steel is used on the front shock mounts, areas of the front passenger-compartment bulkhead, areas of the front subframe mounts, and rear structure
  • 31-percent of the body is constructed with Grade 60 steel

The overall result is a high level of bending and twisting rigidity for the unit body combined with enhanced crashworthiness, all with no additional weight penalty.

ALUMINUM COMPONENTS

The lightweight aluminum hood, front fenders, trunk and trunk frame are formed with an innovative process called blow forming to achieve complex and pleasing shapes with a high level of quality, low cost and lightweight construction. First the raw aluminum panels are placed in a heated mold and warmed to 500-degrees Celsius. Then the aluminum panels are forced into the mold with a high-pressure gas. The result is perfectly formed complex shapes that are not possible with traditional stamping methods.

For rigidity, the trunk lid is composed of an inner structural panel and an outer body panel. This 2-piece aluminum structure is crimped together with a self-piercing rivet that makes the lid highly durable.

DOOR CONSTRUCTION

Safety in side collisions, along with the pursuit of a quality door-closing sound, drove engineers to design all-new door structures. Special beams were applied for side-impact safety in both the front and rear doors.

There is no mistaking the quality sound a well-engineered door makes as it is closes. By positioning door's center of gravity (the height at which its weight is centered) at the same height as the latch, audible vibration and thus the closing sound can be improved. For improved entry and exit the rear doors now open 80-degrees.

TRUNK OPENING

The trunk opening is reinforced to retain rigidity while providing a large, low opening for easier loading. Inside, the opening is finished to hide the hinges and to cover the rain gutters (see Interior section for more information).

WINDSHIELD WIPERS

To decrease wind noise levels and improve appearance, the RL incorporates hidden pivots and wiper arms for its speed-sensing, variable intermittent windshield wipers. The pivots are hidden underneath the trailing edge of the hood line to reduce noise levels, improve aerodynamics, and enhance appearance.

The use of a hidden windshield wiper pivot is a world's first. The hidden pivot improves aerodynamic efficiency and reduces visual distraction when the wipers reverse direction. A new cowl garnish below the windshield wipers also reduces wind noise, contributing to a significant reduction in wind noise.

Another advantage of hiding the wiper pivot is enhanced outward visibility. Hiding the pivot increases the passenger's forward visibility.

AERODYNAMICS

A highly efficient aerodynamic drag coefficient of 0.29 for the Acura RL pays dividends in the form of lower wind noise, improved fuel economy, increased performance, and enhanced stability on the highway. An air dam reduces front end lift force. An engine undercover and floor undercovers further smooth airflow, as do muffler covers and a rear diffuser, which help rear differential's cooling and result in rear lift force reduction.

ACTIVE FRONT LIGHTING SYSTEM

Models equipped with either RL with Technology Packages feature an Active Front Lighting System (AFS). The AFS system uses Xenon High-Intensity Discharge (HID) headlights, 55-watt fog lights, and daytime running lights (DRL).

In the Active Front Lighting System, the left low-beam unit can swivel left, and the right low beam can swivel right, to improve illumination while cornering, or to illuminate around the corner of an intersection. This allows the driver advance warning if a pedestrian, animal, or object is in the way. Each light can swivel up to 20-degrees outboard, with the amount determined based on the vehicle speed and steering input.

The Active Front Lighting system uses the following components:

  • Steering angle sensor
  • Vehicle speed sensor
  • Reverse switch (cancels AFS when car is backing up)
  • Control switch (turns off AFS at driver's discretion)
  • Instrument panel warning light (illuminates when AFS is turned off)
  • Control unit swivels the low beam headlight projector unit via a gearbox motor

AFS swivels either the left or right headlight (not both together) when the following conditions are met:

  • Steering angle is over 12-degrees
  • Vehicle speed is 5 mph or higher (left-hand turns only)
  • Right-hand headlight will swivel even if vehicle is stopped
  • Swivel cancels when speed drops to 3 mph (left-hand turns only)

XENON HIGH-INTENSITY DISCHARGE (HID) HEADLIGHTS

Traditional headlight bulbs illuminate a tungsten filament inside a sealed bulb containing halogen gas. Xenon HID bulbs, however, use a high voltage current that passes between two electrodes to create a plasma arc. This accounts for their brightness and "daylight-like" illumination.

Xenon is superior to tungsten-halogen bulbs in lumens, or lighting power. The Xenon HID bulbs on the RL provide a lighting pattern that is both longer and wider than that of traditional non-Xenon bulbs. In addition, the RL's tungsten-halogen high beams provide a wide illumination spread. The low beams on the RL have a brightness of 825 lumens. For the driver, these advances mean greater illumination for enhanced confidence.

Additionally, the Xenon HID low-beam headlight bulbs have a projected life span of 1,500 hours compared to 1,000 hours for a normal bulb.

LED LIGHTING

The RL features advanced Light Emitting Diode (LED) lighting systems. These include mirror-integrated directional turn signals, each of which features bright LED lights to alert motorists who are alongside when the RL driver is planning to change lanes or make a turn.

Each taillight/brake light assembly has an array of 28 LEDs. The taillights use 14 LEDs, arranged as the perimeter of a circle, and the brake lights use an additional 14 LEDs. When the brakes are applied, all 28 LEDs light up, illuminating the entire area.

The center high-mounted stop lamp (CHMSL) also uses LEDs. The projected service life of the RL LEDs is 2,000 hours.

DAYTIME RUNNING LIGHTS

Similar to the 2008 MDX, RDX and TL, the RL features Daytime Running Lights (DRL) to improve visibility while driving.

5 MPH BUMPERS

To minimize repair costs in minor, low-speed collisions, the RL has 5-mph bumpers front and rear.

NOISE VIBRATION AND HARSHNESS (NVH)

The elimination of undesirable noise, vibration and harshness (NVH) was of primary concern to RL development engineers. Virtually everything that could be the source of these NVH traits was scientifically reviewed and modified during the planning and prototype phases.

Acura wanted to provide RL clients with outstanding horsepower, an innovative all-wheel drive system and large-diameter high-performance tires for advanced handling characteristics. At the same time, they wanted the car to remain refined and quiet for highway cruising while simultaneously generating a stirring high-performance engine sound during acceleration. These attributes, along with light overall vehicle weight, were achieved through the application of innovative technology.

The RL dramatically reduces high frequency and middle-frequency noise attenuation. Road noise attenuation is also improved over both smooth and rough roads. As part of the mission to control weight, Acura used lightweight materials wherever possible in the sound-absorbing package, including lightweight sound insulators instead of traditional heavier materials. In addition, the RL represents Acura's first use of an Active Noise Cancellation® system (ANC®). See Interior section for more information.

Main RL NVH advancements:

Drivetrain

  • Engine mounting system including a hydraulic lower transmission mount
  • Variable volume exhaust mufflers
  • Hood insulator
  • Engine cover and undercoverBody
  • Acoustic roof lining
  • Acoustic front and rear inner fender insulator with high-frequency damping materials

Flooring

  • Lightweight floor insulator
  • Floor undercover

Subframes

  • Floating front and rear subframes with four mounting points

Interior

  • ANC® system for noise control (see Interior section for more information)
  • Lightweight instrument panel damping materials
  • Thinsulate® insulation in selected areas

Trunk

  • Acoustic design with side, front and lid linings

POWER WINDOWS

The side power windows on the RL are made of glass that is 5 mm thick to reduce cabin noise. Each window features an auto-open and auto-close function, an auto-reverse safety feature, as well as key-off operation.

FLUSH GLASS

The Acura RL is the first car in the world to have totally flush side glass where it meets the B-pillars. Normally, a gap of about 5 mm exists between side glass and the B-pillar. On the RL, the window guide is on the glass instead of the window frame, which allows the gap to be eliminated. This means there is one continuous uninterrupted plane running along the front side window, across the B-pillar and all the way to the trailing edge of the rear side window. The benefit is a further reduction in wind noise and an even cleaner, high quality appearance.

EXTERIOR MIRRORS

To reduce wind rush and turbulence, exterior mirror housings need to be small and aerodynamic, without unnecessarily reducing the mirror area. On the RL, the power mirror element is precisely sized to fit inside a compact housing to reduce these unwanted characteristics.

The airflow between the mirror housing and the side window glass is likewise crucial for reducing turbulence and noise. Engineers designed this gap as an expanding V-shape, with the gap narrower at the front and wider at the rear. This helps the airflow decelerate as it flows across the glass, instead of accelerating as it would if the V-angle were to decrease. The result is smoother airflow and less mid- and high-frequency noise.

EXTERIOR PAINT

The exterior paint on the Acura RL uses an environmentally conscious water-based process. The painting procedure begins with an electrodeposition (ED) primer, which is electrically charged in the paint bath to help the primer better adhere to the metal bodywork. The ED primer is cured at high temperature to improve corrosive durability. Next applied is a primer-surfacer that is hand sanded to ensure a smooth surface for better appearance. After a waterborne color basecoat is applied, a pair of clearcoats provides depth while helping to protect the base coat from air pollution, acid rain and sun damage.

Eight different exterior colors are available, including three metallic colors and five pearl colors. All eight colors are selectively available with three different interior colors. The chart below shows the available exterior/interior color combinations (see Interior section for more information).

EXTERIOR COLOR INTERIOR COLOR

Parchment Ebony Taupe
Premium White Pearl x x
Opulent Blue Pearl

x
Redondo Red Pearl x

Carbon Gray Pearl
x x
Platinum Frost Metallic
x x
Nighthawk Black Pearl x x
Lakeshore Silver Metallic
x x
Desert Mist Metallic x

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