Body Design & Structure

The 2005 Acura RL combines its dynamic new exterior and interior design with advanced body and chassis engineering. The result is distinctive and appealing styling, together with super 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

When Acura designers began work on the 2005 RL they wanted to create a taut and athletic shape that conveyed the new performance capabilities of the car without sacrificing the comfort and capability the previous model had achieved.

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

Design Image

Acura designers set out to create the RL with a much more pronounced sporting edge than in the past. To help craft his image, styling cues included the following:

• Taut, athletic body design with European influence
• Aerodynamic lines 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

Packaging

The packaging goal for the 2005 Acura RL was to create a shorter body with reduced overhangs and wider interior dimensions for enhanced comfort and convenience. In comparison to the 2004 3.5 RL, the RL body is three inches shorter with a wheelbase more than four inches shorter. The body is also an inch wider and 2.6 inch taller. The result is enhanced handling capability and maneuverability, and increased passenger volume from 96.2 to 99.1 cu. ft.

Controlling the weight of the RL was important to ensure maximum acceleration, road holding and braking performance. The use of lightweight materials and weight-saving design resulted in a weight gain of only 92 pounds over the previous 3.5 RL, to 3,984 lbs. This modest gain is remarkable, given the dramatically higher vehicle content level, which includes the standard SH-AWD system, side curtain airbags and many other features.

The 2005 Acura RL compares very favorably to its competitors in its class in overall packaging and curb weight. Even though it is equipped with all-wheel drive, its weight is comparable to that of rear-wheel drive competitors and significantly below key competitors with all-wheel drive.

Compared to other vehicles in the RL competitive set, including the Audi A6, BMW 5-Series, Jaguar S-Type, Lexus GS 300 and Mercedes-Benz E Class, the RL is the only vehicle with a standard AWD system, and the only one to offer SH-AWD. The RL is also longer and wider, with significantly wider front and rear track, than its competitors.

In the chart below, boldface type highlights 2005 Acura RL packaging advantages.

Body Structure

Light Weight

Producing a lightweight and rigid unit body was essential to meet engineering goals for the new RL as 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.

Specific RL strategies that were employed to reduce body mass include:

• Aluminum hood, fenders and trunk lid
• 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 2005 Acura RL was also designed with the goal of creating an automobile body which 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.

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 lbs. compared to 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
• The rest of the body is constructed with Grade 60 steel

The overall result is that bending and twisting rigidity for the unit body is superior to that of the 2004 3.5 RL. The 2005 RL also has enhanced crashworthiness with no additional weight penalty.

Aluminum Components

The lightweight aluminum hood, front fenders and trunk are formed with an innovative process called blow forming to achieve complex and pleasing shapes with a high level of quality, low cost and light weight. First the raw aluminum panels are placed in a heated mold and warmed to 500 degrees. Then they 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. 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 closed. 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 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 wiper reverses 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.

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