The Audi A8 L protects its passengers in new, intelligent ways: with a high-strength body, adaptive restraint systems and the new Audi pre sense safety system. It is available in a standard version and in three expanded levels.
In the standard variant – Audi pre sense basic – the system uses the information from the ESP stabilization program. If they signal a critical situation, such as skidding or maximum braking, the control unit intervenes. Depending on the situation, it activates the hazard warning lights and closes the side windows and the sunroof; it also partly or fully tensions the front seat belts. Small electric motors trigger this process, which is reversible; if the situation is averted without an accident, the belts are released again.
The new safety system is available in a number of versions, two of which are Audi pre sense front and Audi pre sense rear. They are tightly coupled with the optional assistance systems adaptive cruise control with stop & go function and Audi side assist, making them particularly differentiated and capable.
The Audi pre sense front system protects against rear-end collisions with moving vehicles ahead. It warns the driver in three stages. If the sedan is approaching a slower moving car ahead, a warning gong sounds while a red signal lights up in the driver information system display. Parallel to this, the brake system is prefilled and the air shocks and dampers of the suspension are set to hard. The warning is intended to persuade the driver to apply the brakes or take evasive action, which is often the better strategy.
If the driver remains passive, the acute warning – a warning jolt produced by the rapid generation of pressure in the brake system – is issued in stage 2. The seatbelts are lightly tensioned at the same time. If the driver now depresses the pedal, the hydraulic brake assist system handles precise braking relative to the preceding vehicle. The fact that the system is already prefilled saves between 0.1 to 0.2 seconds, or more than seven meters (22.97 ft) at a speed of 130 km/h (80.78 mph).
Should the driver also ignore the warning jolt, the third stage is activated – partial braking that initially slows the A8 L at a rate of 3 m/s2. The windows and sunroof are closed, and the hazard warning lights are activated.
The last resort: maximum braking
If the sedan is equipped with the full version of Audi pre sense – Audi pre sense plus, which is part of the assistance package – a fourth stage follows, if necessary. The system now increases deceleration to 5 m/s² and pulls the belts tight. This is followed by a final braking phase with maximum braking. It begins about half a second before impact – at this point there is no longer any time for evasive action. The force of the collision and its consequences are greatly reduced, for by impact the A8 L has cut its speed by as much as 40 km/h (24.85 mph).
Audi pre sense rear mitigates the consequences of a rear-end collision; it closes the windows and sunroof and tightens the belts. If the A8 L is equipped with seats with a memory function, the upper backrest of the front seats and the optional individual seats in the rear, plus the front headrests are moved into a position that reduces the risk of whiplash. In addition, the (optional) pneumatic side bolsters in the front seats are filled with air.
Excellent protection: crash safety
The new Audi A8 L has a body that offers excellent protection against all types of collisions. In a frontal collision, four load paths distribute the forces optimally to each side of the vehicle. Two of these are located in the upper portions of the fenders, the others in the longitudinal members and the buffers installed in front of the subframe for the engine and the front axle. The other vehicle involved in the accident also benefits from the homogenous shape of the front.
A crossmember manufactured out of a double-box section and bent into the shape of an omega provides additional protection for the passenger cell. The crossmember is located on a line with the footwells and diverts the forces into the floor and the A-pillars. The longitudinal members in the floor panel come together in the shape of an arrow below the rear bench seat. Together with the center tunnel they constitute the body’s strongest node. Large beams in the rear protect the passenger cell; the rear wheels are braced against the side sills in the event of a collision.
Standing guard in the large sedan’s cabin is the adaptive restraint system. It is networked with Audi pre sense and draws its own information from eight pressure sensors and acceleration sensors. It intelligently manages the interplay between the airbags and the belt force limiters to offer outstanding protection to passengers of any size.
Sensors on the front seat rails detect how far forward or back the seat is positioned. Because the control unit then knows the approximate position of the passenger, it can ensure that optimal use is made of the distance over which the upper body is slowed by the belt and the airbag. Audi pre sense reduces this distance by roughly ten centimeters (3.94 in) because the belts are tensioned before the crash occurs.
If a passenger – typically a smaller person – is sitting close to an airbag, a portion of the air is quickly expelled via valves after the airbag inflates so that the head and chest are gathered in more gently by the airbag. In a hard crash or with large occupants who sit farther back, the valves remain closed longer. The variable belt force limiters are likewise designed to be adaptive. They control belt tension so that chest loading remains as low as possible.
The structural design of the seats and headrests is another important element of safety design, especially in the case of a rear-end collision. These types of accidents frequently occur at traffic lights, usually with impact speeds between 15 and 50 km/h (9.32 and 31.07 mph). The integral head restraint system from Audi acts here to counter the risk of whiplash injuries.
Four side airbags in the backrests of the front seats and the outside rear seats stand at the ready to catch the pelvic area and chest of the occupants in the event of a side-impact collision. Stretching from the A- to the C-pillars, the head airbag system opens like a curtain from the roof frame to the door sill. All of the seats in the new A8 L have three-point automatic seatbelts with tension limiters. The rear seats are equipped with Isofix fixtures for the safety seats of the youngest passengers.
The new A8 L satisfies all legal requirements for the protection of pedestrians in the event of a collision. A foam between the front bumper and its crossmember makes the impact slightly easier on the knees. If the head should hit the hood, the aluminum panel can deform over a wide range. The gap between it and the hard components in the engine compartment is large.
The standard insurance category crash – a parking lot crash – has no major financial consequences. The aluminum crash boxes bolted in front of the crossmembers at both the front and at the rear of the car are relatively easy to replace.
The front and rear sensors remain undamaged in the event of a low-speed parking crash because they are cleverly integrated into the deformable covering of the bumpers.
The equipment and data specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.