A safety device for a motor vehicle includes a deformation element which is arranged between a bumper beam and a side rail and moves into the side rail in the event of an impact. The deformation element is configured in the form of an evertable tubular member having a side-rail-proximal rear end provided with an abutment ring. Operatively connected to the deformation element is an actuator which is provided to release a displacement of the deformation element into the side rail in a predefined speed range by liberating the abutment ring in relation to the side rail in a release position, and to block the displacement of the deformation element into the side rail, when the speed range is exceeded or a vehicle speed is below the speed range, by locking the abutment ring in relation to the side rail in an engagement position.