The dealer returned the car to my office today...such service. They said that one of the shields under car was bent...which caused the grinding noise. I am not sure which shield it was, because the porter did not bring any paperwork. I am still not sold on the thumping form under the car being completely gone. They want to replace my back bumper to because they can not restore the finish that the protectant destroyed. The bumpers come unfinished and they have to send them out to be painted. I am not sure if I like this idea. Anyways the shield will probably end up being the one that you had trouble with too.