I find that the finest steel whool you can buy (number rating is #0000) and a little bit of liquid dish soap (dawn, palmolive whatever your favorite is, doesn't matter) will take it right off after a few washings. Also works very well for taking bugs off in the winter. Just take one piece, break it in half (save the other half for next time) add some of the soap, wet it a bit, and start scrubbing on wet windows and it works great. You don't have to really work it in there, just scrub normally and you shouldn't have any problems. Just DO NOT use it on the side mirrors (scratched mine) or the headlight covers (including fogs)...it will put faint scratches in them. You CAN use it on the windshield, side windows, and rear glass.