Variable M Differential Lock
The variable, speed-sensing M differential lock on the rear axle ensures that BMW M vehicles handle with the best possible traction even in highly demanding driving situations.
A conventional differential lock transmits the overall drive power to the wheels depending on the momentum and forces conveyed by the wheel running on the more slippery side, i.e. with a lower frictional coefficient.
Wherever this frictional coefficient is particularly low, for example on snow, gravel or ice, the lack of traction means that overall drive power is dramatically reduced.
The variable M differential lock offers a decisive advantage even if the wheels are running on totally different surfaces with a very significant difference in their frictional coefficient. If there is an increasing difference in the speed of rotation on the two drive wheels, the system responds by increasing locking action. As a result, the wheel under less load - for example the inner wheel in a bend on a fast serpentine road - can no longer cause an overall drop in drive force. Forward drive power remains fully available.
In extreme cases, up to 100% of power can be channelled to the wheel with the better grip. In winter, this results in a significant boost to traction. The variable M differential lock ensures that BMW M vehicles handle with remarkable sure-footedness and deliver excellent driving stability.