Adaptive cruise control builds on the functionalities of the
cruise control system and within certain system limits,
maintains the driver-selected comfort spacing from the vehicle
in front automatically. The system uses a special radar sensor
to measure the distance to the vehicle ahead. If the distance is
too small, the system reduces speed moderately by easing the
throttle or automatically applying the brakes, up to
approximately 25% of maximum vehicle deceleration. Once the road
ahead is clear again, adaptive cruise control accelerates the
car up to the previously set speed. If the braking process
activated by the adaptive cruise control does not decelerate the
vehicle sufficiently, an acoustic signal is triggered
immediately to warn the driver to intervene manually. Adaptive
cruise control does not react to stationary objects or
approaching vehicles. It should not be used on winding roads or
in adverse weather conditions such as fog, ice or heavy rain.