See also:

Tire inflation pressure values over 100 mph/160 km/h
320i   328i 335i ...

The concept
The following can be operated using the buttons and the thumbwheel on the steering wheel: Current audio source. Redial on telephone*. Activation of the voice activation system*. ...

Switching on automatically
With the engine running or the ignition switched on, shift the selector lever into position R. The image of the rear view camera is displayed when the system has been switched on using iDrive. ...