Tom, Are you sure that the mark on your windshield is not caused by the fact that you have placed a coating (Rain-X) on it? It occurs to me that the Rain-X might be wearing away, and that is what you're seeing. Have you tried to remove the Rain-X and anything else that's on the windshield? (e.g. I suspect that the dealer waxed mine before they delivered my car.) Regards, Jerry Arlington, TX (17-Aug-96, 11:01) '95 540i-6 spd