quattro – the all-wheel drive optimised for efficiency


quattro with crown centre differential

quattro is a permanent all-wheel drive system. If the wheels of one axle lose grip and threaten to spin, the drive torque is redirected to the other axle – automatically and continuously distributed through the self-locking centre differential with wheel-selective torque control. The basic distribution is 40:60 – with 40% of the power going to the front axle and 60% to the rear. If necessary, however, up to 70% can be directed to the front and up to 85% to the rear to counteract wheel slip.

 

The advantage: more grip when accelerating and greater safety thanks to the exceptional roadholding. So much for the technology. But what makes quattro unique is really the driving feel. “It’s like you’re stuck to the road,” some customers say. We put it this way: quattro gives you a better feel for the road and thus more safety.

With the sport differential, it’s like driving on rails.

The optional quattro with sport differential further reinforces this inimitable quattro feeling. Vehicles tend to understeer when turning into and moving through bends. This is a normal physical process whereby a moving body resists a change in direction. The elastic tyres and the suspension mounts tense up until the vehicle adopts the new direction. When accelerating into a bend, the load on the front axle is reduced and it can therefore transfer less lateral force to the tyres – the vehicle understeers.

This tendency is largely counteracted with the sport differential on the rear axle. This is because a superposition unit with two gear stages has been added to the quattro rear-axle differential on the left and right. These ensure that the individual wheels on the rear axle receive different levels of drive torque. The clutches are activated by an electrohydraulic actuator. Depending on factors such as steering angle, lateral acceleration, yaw angle and road speed, the control unit calculates the most suitable distribution of torque to the wheels for every driving situation. When the steering wheel is turned, for example, or the car accelerated in a bend, power is redirected specifically to the outer rear wheel.

 

This has the effect of pushing the car into the bend so that it follows the angle of the front wheels. The difference in tractive force between the left and right wheels exerts an additional steering effect, so that the corrections the driver has previously had to make to the steering wheel become virtually unnecessary. This allows precise control and sporty handling as well as greater agility along with outstanding traction.

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