HandlingBack to overview
The Audi S8** offers outstanding handling straight from the factory – with a bundle of top technologies that comes as standard: predictive active suspension, dynamic all-wheel steering and quattro with sport differential. This unique combination opens up an unprecedented spectrum of possibilities for the driving experience. The characteristics range from the gentle rolling of a classical luxury sedan to the dynamic, taut handling of a sports car.
A new chapter for technology: predictive active suspension
With the predictive active suspension, the brand with the four rings is opening a new chapter in the history of suspension technology. The high-tech system works in combination with the air suspension featuring controlled damping and exerts a special influence on the handling. The active suspension can raise or press down each wheel of the new S8** at any point of the suspension. It is therefore possible for the first time to actively control the position of the body in any driving situation. During dynamic driving, the sedan turns in precisely, body movements are significantly reduced, almost without rolling or pitching during acceleration or braking. If, on the other hand, the driver chooses the “comfort +” mode via Audi drive select, the new Audi S8** glides smoothly over any surface irregularities like a classical luxury sedan.
Even negotiating sweeping curves on country roads and freeways becomes a comfortable experience: Thanks to the new curve tilting function, the body leans into curves by as much as 3 degrees, thus reducing the forces acting on the occupants. The system allows for the greatest perceptible comfort at speeds between 80 and 130 km/h (49.7 and 80.8 mph) and lateral acceleration of up to 0.4g. In the “dynamic” drive select mode, the S8** turns in precisely. The maximum roll angle during fast cornering is just roughly 2.5 degrees compared with around 5 degrees with the standard suspension. The situational distribution of roll moments enables self-steering that is neutral or minimally oversteering. This makes the S8** feel extremely safe and easy to steer, and allows it to go around bends with great precision as if it were on rails. For straight-line travel in the “comfort +” mode, the predictive active suspension can equally reduce the forces acting on the human body. When accelerating hard or braking up to a moderate level, it equalizes the body’s pitching movements. The slight overcompensation that it realizes means the occupants are pushed very gently into their seats during braking.
Another new function that the predictive active suspension brings with it is convenience entry. Here, the body is quickly raised by up to 50 mm (2.0 in) when the doors are opened to make getting in and out even more comfortable.
A small electric motor that is supplied by the 48-volt main electrical system is placed on the wheel suspension of each wheel on the new Audi S8**. A belt drive and a compact strain wave gearing step up the electric motor’s torque almost 200-fold to 1,100 Nm (811.3 lb-ft) and apply it to a steel rotary tube. This is permanently attached to a preloaded titanium rod located inside it. The rod is more than 40 centimeters (15.7 in) long, around 22 millimeters (0.9 in) thick and, despite its high strength, can be turned through more than 20 degrees. From the end of the rotating rod, the force is transmitted to the suspension via a lever and a coupling rod. On the front axle, it acts on the suspension strut, and on the rear axle, it acts on the transverse link. Whenever driving physics attempts to push the body into the wheel, the predictive active suspension counteracts this.
It obtains its information from the electronic chassis platform (ECP) every five milliseconds – two sets of power electronics prepare it for the electric motors. The ECP is the central suspension control unit that also manages the dynamic all-wheel steering, the sport differential, the controlled damping and the air suspension. From the driving-relevant data that it gathers via various sensors, it calculates the optimal function of these systems and instantly and precisely coordinates them. For its part, the ECP uses the images from the onboard camera to detect significant irregularities in the road surface. The range for the predictive function in front of the vehicle extends to around 15 meters (49.2 ft). In poor visibility conditions, snow or at particularly high speeds, the system operates without the predictive element.
In the event of an impending side impact at more than 25 km/h (15.5 mph), the predictive active suspension in conjunction with the pre sense 360° safety system very quickly raises the body by up to 80 millimeters (3.1 in) on the side of the impact. As a result, the other party in the accident collides with a lower, more resistant zone of the sedan. The side sills and floor structure accommodate a large portion of the impact forces. Deformation of the cabin and the loads acting on the occupants, above all in the chest and abdominal areas, can thus be reduced by up to 50 percent compared with a lateral collision in which the suspension is not raised.
Redefining limits: dynamic all-wheel steering
Dynamic all-wheel steering is the perfect partner for the predictive active suspension. This allows the steering angles at the front and rear axles to be adjusted independently of one another. In conjunction with the active suspension, the system provides an almost instantaneous steering response with outstanding stability and conveys intense, finely differentiated feedback from the road to the driver at all times.
At the front axle of the new Audi S8**, dynamic steering features strain wave gearing with a ratio that changes depending on the driving situation and speed – as the speed increases, it becomes increasingly indirect. The rear wheels are turned by an electric spindle drive via two track rods, which makes maneuvering and steering on tight bends significantly easier and reduces the turning circle by about one meter (3.3 ft). At medium and high speeds, the rear wheels are turned by up to 1.5 degrees in the same direction as the front wheels. Thanks to this coordinated steering, the new Audi S8** is stable and masterful on the road even in the event of a sudden lane change or avoidance maneuvers.
With both steering systems working together, the overall steering ratio varies within a range of 9.5 to 17.0. Via Audi drive select, the driver can set the ratio and the characteristics of the dynamic all-wheel steering to a choice of three levels.
Active torque vectoring: the sport differential
Another standard feature of the new Audi S8** is the sport differential. It ensures exhilarating driving dynamics in all situations and is part of the quattro permanent all-wheel drive. During dynamic cornering, it distributes drive torque between the wheels on the rear axle as required. This active torque vectoring improves traction, dynamics and stability. To do so, it integrates a transmission stage on each side that is engaged via an electro-hydraulic multi-plate clutch.
When turning into or accelerating in a curve, most of the torque is directed to the outside wheel. The car is literally turned into the curve and thereby nips any hint of understeer in the bud. In case of oversteer, the sport differential stabilizes the new S8** by shifting torque to the wheel on the inside of the curve. The wheel-selective torque control functions via the wheel brakes and perfects the action of the sport differential by gently braking the front wheel on the inside of the curve that is under less load. This ensures near perfect steering behavior when cornering at high speed in the Audi S8**.
The Audi drive select dynamic handling system also comes as standard in the new Audi S8**. This allows the driver to determine how systems like the sport differential, the predictive active suspension with adaptive air suspension, dynamic all-wheel steering, the engine and the eight-speed tiptronic should work. With Audi drive select, there are five profiles to choose from: comfort + (new), auto, dynamic, efficiency and individual.
** The collective fuel consumption values of all models named and available on the German market can be found in the list provided at the end of this press information.
All terms marked in the text are explained in detail in the technology lexicon at www.audi-mediacenter.com/en/technology-lexicon.
The equipment, data and prices specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.