ACC.

The ACC automatic distance control from Volkswagen builds on the familiar cruise control system by adding a radar sensor. When activated, the system maintains a preset distance from the vehicle ahead by automatically adjusting the car’s speed accordingly. This makes the ACC automatic distance control a major strain-relieving, comfort-enhancing driver aid.

The ACC automatic distance control is based around a radar sensor with a range of up to 200 metres and a beam angle of 12 degrees. The radar sensor and control unit are combined into a single unit which is located – on the Passat for example – behind the Volkswagen badge in the radiator grille.

Using the signals from the radar sensor, the control unit computes not just the distance to the vehicle ahead but also the car’s speed relative to it, as well as its lateral offset on multi-lane carriageways. If there are several vehicles within the sensor’s field of coverage at the same time, this information is used to select which of the vehicles the system should track. The radar sensor is not capable of detecting stationary obstructions, such as the end of a tailback or crash barriers, however.

If approaching a slower vehicle ahead or another vehicle cuts in front, the automatic distance control slows down the car by initiating corrective controls in the engine management and, if necessary, in the braking system too. If the required rate of deceleration exceeds 30 percent of the vehicle’s maximum stopping power, the driver will be prompted by visual and audible warning signals to apply the brakes manually.