4MOTION.

The Torsen differential is a mechanical self-locking centre differential which regulates the power between the front and rear axles according to demand. The word "Torsen" is made up of the words "torque" and "sensing", indicating that the differential operates on the basis of torque sensing. It responds to varying rotational forces between the input and output shafts (front and rear axle). This enables variable distribution of the driving torque between the axles. On a Torsen differential the two output gears are interconnected by worm gears. They limit high differential rotation speeds, but still balance the speeds when cornering.

On the Phaeton the basic configuration of the Torsen differential is selected such that the driving forces are normally distributed 50:50 across the front and rear axles. In case of slip, the Torsen differential diverts as much as 20 percent of the driving power to the axle with the better traction (max. 70:30, or 30:70). The adjustment is made steplessly and with no time delay. The locking effect of the Torsen differential increases automatically along with the load. In contrast to a "speed sensing" viscous lock, it operates in "torque sensing" mode. The advantage of this method is the lack of torsional stress when cornering, as the differential rotation speeds the vehicle seeks to bring about are in fact permitted.