The concept
If the vehicle is equipped with Active Cruise Control with Stop & Go, the collision warning is controlled via the cruise control radar sensor.
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:
Sitting safely
The ideal seating position can make a vital contribution
to relaxed, fatigue-free driving.
The seating position plays an important role in
an accident in combination with:
▷ Safety belts.
...
Dynamic, efficient and innovative: the new BMW 3 ActiveHybrid
In autumn 2012 a further model will join the BMW 3-Series. In the new 3
ActiveHybrid - a full hybrid at the premium end of the sports sedan class - the
innovative BMW ActiveHybrid powertrain techn ...
Resuming cruising speed
Press button 4:
The stored speed is resumed and maintained ...
