billo

Could also be pebbles lodged in the rear bumper. Hit the area just left of the license plate fairly hard about 10-20 times. You will be surprised to see how much road debris falls out.

marks_lude

i think i know what ur problem is maybe....

check the bumper clips in the bottom center of the bumper (under the car). they could have been broken during ur rear ending.

i just installed a hitch, and couldnt get those clips back in easily and was in a rush, so i left them out. the bumper feels solid, but that flap at the bottom rattles loudly at certain rpms. im 99% sure its this on my car because it only happened after i messed with the bumper for the hitch install, and the only thing thats different from before the install.