Abstract: An air dam comprised of a molded plastic deflector panel is mounted beneath the front end structure of the vehicle forwardly of the front wheels. The deflector panel is subject to engagement with a parking bumper or other obstruction and is elastically yieldably movable upon such engagement within a certain range of elastic deformation and is subject to breakage upon deformation beyond the limit of the range of elastic deformation. A switch is mounted on the front end structure rearwardly of the molded plastic deflector panel and has an associated sensor which is operatively associated with the deflector panel and is adapted to actuate the switch in response to yielding movement of the deflector panel within the range of elastic deformation.