The concept
The parking brake is primarily intended to prevent the vehicle from rolling while parked; it brakes the rear wheels.

See also:
Automatic deactivation during forward travel
The system switches off when a certain driving
distance or speed is exceeded.
Switch the system back on if necessary. ...
Distance
Selecting a distance
Adjust the distance according to the traffic
and weather conditions; otherwise, there is the
danger of an accident occurring. Maintain the
prescribed safety distance.φ ...
Requirements
Via the Control Display, set a language that is
also supported by the voice activation system
so that the spoken commands can be identified.
Set the language. ...
