The Haldex coupling on our 4DRIVE permanent four-wheel drive system enables the driving power to be distributed variably between the front and rear wheels. It also ensures the effectiveness of electronic systems such as the anti-lock braking system, traction control or electronic differential lock. To achieve this, additional information is taken into account via a computer. Its control system balances not just traction and the resulting differences in speed between the wheels, but also further variables such as handling conditions and drive torque. This enables better interaction with the electronic systems and improves the distribution of driving power with regard to directional stability and safety. The computer uses data from the wheel speed sensors and engine management to react in the best way to the situation.