Parking Distance Control (PDC) systems assist the driver in manouvering out of a tight spot, and warning them of any obstacles nearby.
Engaging the reverse gear activates the electronic control unit. At the same time this creates a protective zone around the bumper. An acoustic signal is emitted when any obstacle comes into the controlled area behind the car. The warning beeps get faster as the distance to the obstacle is reduced - so that a collision can be avoided.