See also:

Deactivating DISTRONIC PLUS
WARNING The DISTRONIC PLUS switches off and releases the brakes when the vehicle decelerates below the minimum speed of 20 mph (30 km/h) by operation of the system unless the DISTRONIC PLUS ...

Traction
Traction is the result of friction between the tires and the road surface. ...

Activation conditions
You can activate the HOLD function if: Rthe vehicle is stationary. Rthe engine is running. Rthe driver's door is closed or if your seat belt is fastened. Rthe electric parking brake is released. ...