I had to sign up to share some valuable info with everyone. Bar Keepers Friend. This product works great for cleaning vape residue off car windows. It's a cleaner that's been around since 1882 for cleaning stainless, copper, tile, ceramic, etc., but it has so many more uses. I found out about this stuff while looking for a product for removing soap scum build up off glass shower doors (which I found it to do better than any other cleaner), so I figured I would try it on my car windows and it works awesome. I'll usually hit the windows with regular window cleaner after (Sprayway is also the best for this) just to restore complete clarity, but I probably don't even need to. A big bottle seems to last for ever. Try it out!