Abstract: Device for motor vehicles designed to prevent traffic accidents or to reduce their injurious consequences. The extent of injuries in traffic accidents can be reduced significantly by employing the vehicle bumper (1) as a crumple (deformation) zone. A sensor (2) is used to record this distance from and speed relative to an obstacle in the direction of travel. When a collision is unavoidable, one end of the bumper (1) is projected outward by a propellant charge (13) so that, together with a strut (17, 22, 24), if forms a crumple zone ahead of the vehicle. The device can also be provided with a system to warn of dangerous traffic situations, and to brake the vehicle automatically or reduce its speed if the risk of a collision exists. In the case of trucks and buses, the bumper (1) may be deployed by means of a pneumatic cylinder (4) and valve (7), which are controlled by the vehicle's ordinary speedometer. The bumper remains depolyed above a certain threshold speed.