There's a number of YouTube videos using very fine steel wool on your windshield. The problem with any windshield after a period of time you get all these little nicks and micro fine scratches and it's never really super clear. By using very fine steel wool it removes these fine scratches. I have used very fine sandpaper on discolored headlight lenses to remove the discoloration and it came out perfect then I coated with a liquid coating to maintain it. If you can use sandpaper on headlights, why can't you use very fine steel wool on windshields?