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

See also:
Activating HDC
Press the button; the LED above
the button
lights up. ...
Backrest width
Change the width of the backrest using the side
wings to adjust the lateral support.
To make it easier to enter and exit the vehicle,
the backrest width temporarily opens fully. ...
BMW X5 xDrive50i: BMW's Twin-Turbocharged V-8.
The new BMW X5 xDrive50i takes its place as the flagship of the X5 family,
yielding 400 horsepower at 5,500 rpm and 450 lb-ft of torque at 1,750 - 4,500
rpm from its twin-turbocharged 4.4 liter V- ...
