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

See also:
Buttons on the remote control
1 Unlocking
2 Locking
3 Opening the tailgate
4 Panic mode, headlamp courtesy delay feature ...
Vehicle Overview
BMW calls the 2006 version of its flagship 7 Series sedan a midsize
freshening rather than a redesign. Launched as a 2002 model, the
current-generation rear-wheel-drive 7 Series has been available ...
Visual warning
The approach of the vehicle to an object can be
shown on the Control Display.
When the distance to an object is small, a red bar
is shown in front of the vehicle, as it is in the PDC
display.
...
