My windshield had been plagued with spots since the day I took delivery. I tried all of the usual auto glass cleaners to no avail. Having seen this polish in the Griot's Garage (http://www.griotsgarage.com)catalog I decided to go ahead and give it a shot. (At this point it was that or try to get the dealer to remove them.) Well, after about 5 minutes with the polish the spots are gone and I am very pleased, since I know that with our hard water and summer rain the spots will be back. Definately the best way to really clean glass with stubborn deposists or little scratches.