See also:

BAS PLUS (Brake Assist System Plus)
BAS PLUS is only available in vehicles equipped with DISTRONIC PLUS. Observe the "Important safety notes" section. At speeds above approximately 20 mph (30 km/h), BAS PLUS assists ...

Important safety notes
WARNING If you tow the vehicle, you must use a rigid towing bar if:  - the engine is not running.  - there is a brake system malfunction.  - there is a malfunction in ...

Applying automatically
Your vehicle's electric parking brake is automatically applied if DISTRONIC PLUS or the HOLD function bring the vehicle to a standstill, or are engaged to keep the vehicle stationary. In addit ...