Was washing the car yesterday and decided to put a magnet to my rear bumper support. I know my front one is steel cause it is really rusty but the rear support looks new, so I got out a magnet and surprise my rear bumper support is aluminum. Does anyone else have a car with a steel and an aluminum bumper support on it. Not the original owner so not sure if one or the other has been changed but I would guess they haven't. Why would Buick do that?