If bumpers could crack that'd be cool (but probably a difficult thing to do) but what I'm sure can be done, is making a sound for a scraping bumper (or any scraping part for the matter) if we slide on a guard rail we want to hear a skshhhhhhhhhhhhh if our bumper is hitting the ground and coming back up then hitting the ground again, we want to hear a thump, thump, thump and it is certainly possible because we have the sound of the flat tire.
cracking is ggez just make the bumper out of extremely dense nodebeams and make them all breakgroups ( ͡° ͜ʖ ͡°)