As an aside, after I recently cleaned the glass door to my master bathroom shower, I decided a couple of layers of
UPGP might help it stay cleaner longer and/or make it easier to clean. It seems to be serving that purpose, but the door fogs much worse than the untreated glass ever did. It fogs up much more quickly and there is noticeably more fog. Not a huge deal, but I would recommend against putting UPGP on a vehicle's interior glass.