The 4x4 drive is provided by the 5th generation Haldex coupling, which automatically engages the rear wheel drive to guarantee the optimal transmission of power to the road. This is controlled by the Haldex ECU, based on the data from the engine, ABS/ESC sensors and steering wheel angle sensor. The all wheel drive is fully compatible with the electronic stability systems (ABS, ESC) and continually modulates the torque sent to the rear wheels.
During acceleration, the rear wheels are most effective at transfering power, so the Haldex coupling transfers as much torque as possible to the rear wheels. On the other hand, when driving at higher speeds, the rear wheel is engaged only when necessary. In case of ESC intervention, the control of the Haldex coupling is taken over by the ABS/ESC control unit. There is no need to transfer the torque to the rear wheels while braking, so the coupling is disengaged.