This has happened a few times, but I have never been able to figure out what it could possibly be. I believe that all 3 times over the course of a year, it has been when I was reversing. It sounds almost like a flimsy piece of metal being dragged on the ground, also sounds as if its in the front part of the car. I checked brakes, anything that may have been lose hanging from the car, ect... Its done it when the car was cold, and also when it was hot. I don't see anything that could be making the noise. Anyone else heard this noise before? I know its kind of vague, so not hoping for much help on this.