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

See also:
Ventilation in rear
Ventilation in rear
1. Use the thumbwheels to smoothly open and
close the air vents
2. Thumbwheels to adjust temperature in upper
body region; can be adjusted separately
for left and right:
...
Adjusting the volume
1. "CD/Multimedia", "Radio" or "Settings".
2. "Tone".
3. "Volume settings".
4. Select the desired volume setting.
5. To adjust: turn the control ...
Switching off automatically
System switches off: above approx. 9 mph/
15 km/h.
Switch on the system again if necessary. ...
