Analysis of information sources in references of the Wikipedia article "Bumper (car)" in English language version.
But in 1974, everything changed: new American regulations imposed new bumpers, and made it almost impossible to market a car with variable suspension height without heavy and very expensive technical modifications. Citroën had to throw in the towel in the United States after hoping in vain for a waiver.
The intention of the current U.S. bumper standard is to reduce damage to the bumper system and thus provide American consumers with a lower bumper damage replacement and repair cost, while also maintaining the integrity of the safety systems.
The reduction in speed divided by the time over which it takes place defines deceleration. Injury-producing forces are proportional to the deceleration experienced by the occupant. Occupant protection aims at reducing these forces by spreading the occupant's changes in speed over longer times. The theoretical best protection would be for the occupant to slow down from the initial vehicle speed to zero speed at a constant deceleration using the entire distance between the occupant's body and the vehicle's point of impact. In the previous example of an initial speed of 50 km/h, and assuming the driver is seated 2.5 m behind the front bumper, the resulting average deceleration would be 4 G, uncomfortable but unlikely to produce even a minor injury.
UN Regulation No. 58: Uniform provisions concerning the approval of [1] Rear underrun protective devices (RUPDs) [II] Vehicles with regard to the installation of an RUPD of an approved type [III ]Vehicles with regard to their rear underrun protection (RUP)]
But in 1974, everything changed: new American regulations imposed new bumpers, and made it almost impossible to market a car with variable suspension height without heavy and very expensive technical modifications. Citroën had to throw in the towel in the United States after hoping in vain for a waiver.
