See also:

Deactivating HDC
Press the button again; the LED goes out. HDC is automatically deactivated above approx. 37 mph/60 km/h. ...

Contacts
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Automatic-Transmission
Starting the engine 1. Depress the brake pedal. 2. Press the Start/Stop button. The ignition is activated automatically for a certain time and is stopped as soon as the engine starts. ...