See also:

Condensation under the parked vehicle
When using the automatic climate control, condensation water develops that exits underneath the vehicle. Therefore, traces of condensed water under the vehicle are normal. ...

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*. ...

Remove attached parts following use
Remove unneeded auxiliary mirrors, roof or rear luggage racks after use. Attached parts on the vehicle impair the aerodynamics and increase the fuel consumption. ...