Front Assist is based on the ordinary cruise control system. If the car in front is moving more slowly, your selected speed is reduced to match. This is achieved by automatic application of the brakes and intervention to control your car's acceleration. By selecting different time gaps, you can adjust the distance maintained. Apart from its function in Front Assist, the radar system also detects situations where the distance to the car in front is critical and helps to reduce your car's stopping distance when needed. The system also warns you of a dangerous situation with visual and sound signals and with a braking jolt.
Article source: www.volkswagen.co.uk