See also:

The windshield wipers are obstructed
Leaves or snow, for example, may be obstructing the windshield wiper movement. The wiper motor has been deactivated. - For safety reasons, you should remove the SmartKey from the ignition lock. ...

Important safety notes
WARNING When leaving the vehicle, always remove the SmartKey from the ignition lock. Always take the SmartKey with you and lock the vehicle. Do not leave children unattended in the vehicle ...

The M-Class also protects its occupants after a crash
As part of the POST-SAFE® functions, the new M-Class can activate a variety of systems which can contribute towards avoiding post-accident risks. After a more serious crash, the hazard warning lig ...