Bumpers should be designed to protect car bodies from damage in low-speed collisions, absorbing crash energy without significant damage to the bumper itself. A 1991 Institute study of cars brought to 16 insurance drive-in claims centers in 4 metropolitan areas found about 20 percent of all claims for auto damage involve parking lot collisions. For a bumper to be effective, there must be some distance between the reinforcement bar and the sheet metal it should protect.
Bumpers vary a lot in terms of both components and performance.
This is true among cars of similar size and type and among cars from the same automaker. Some bumper designs put more emphasis on style than protection. As a result, even the most minor collisions can mean expensive damage. Lights built into bumpers may be stylish, too, but they can sustain damage in low-speed crashes. Bumpers used to be stronger.