The concept
The system issues a two-phase warning of a danger of collision at speeds above approx.
10 mph/15 km/h. The time of these warnings may vary depending on the current driving situation.
The collision warning is available even if cruise control has been deactivated.

It responds to stationary or moving objects that are within the detection range of the radar system.
When the vehicle is intentionally brought into contact with a vehicle, the collision warning is delayed to avoid false warnings.
See also:
Observe the following when refueling
The fuel tank is full when the filler nozzle clicks
off the first time.
Handling fuels
Obey safety regulations posted at the gas
station. ...
Storing
1. Switch on the ignition.
2. Set the desired position.
3. Press the button. The LED in the
button lights up.
4. Press the desired button 1 or 2. The LED
goes out.
If the M button is pressed ...
Switching on automatically
Select transmission position R with the engine
running.
The images from Top View and PDC are displayed
when the system has been switched on
using iDrive. ...
