Had a similar rattle also seemed coming from the lower area passenger seat somewhere. I thought it might have been a wire somewhere but could not find it. Also took those mudflap things off in front of the front wheels as it didnt do it at low speed so thought it was wind related. Did not fix it. Then after letting someone else drive my car, I found out the rattle came from the enginebay and not near the passenger side. http://www.opelaus.com/forums/showth...-of-the-engine