Really REALLY bad eyesight, and a 19 year old windshield. A tuffy to scrub down the windshield in side and out. Rinse with tap water. Swab the glass down with alcohol and rub to remove grime and plastic vapor film (inside). Rinse off with distilled water while wiping with a microfiber towel. I've tried Invisible This and X That but neither removed that danged plastic vapor film on the inside. I could swear many of those "extra clear" invisible products are nothing more than regular stuff diluted with a lot of distilled water. Distilled water takes all the soap film off and that seems to be the thing that I gripe about the most.