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

See also:
Stowing cargo
BMW X5
BMW X5
BMW X6
BMW X6
▷ Very heavy cargo: when the rear seat is not
occupied, secure each of the outer safety
belts in the BMW X5 in the opposite buckle.
▷ Heavy cargo: ...
Using the door lock
General information
Do not lock from the outside
Do not lock the vehicle from the outside if
there are people in it, as the vehicle cannot be
unlocked from inside without special knowledge.
...
Adjusting
Vehicle
...
