Fairly new to contemporary car modeling, though many years in model railroading. Recently saw some rather old articles/videos using Future (now Pledge) floor polish to clear coat completed models.
Was aware of its use on clear plastic, but not as a final clearcoat over an entire painted model.
Any here use it that way and, if so, will it yellow with age?

I use if for armor and have never had a problem with yellowing.

Same here. Long time working models of aircraft and armor. Used with airbrush or paint brush it goes on smooth and clear. I have never seen any yellow tint when used on enamels, acrylics, or decals. Multiple coats look great clear and smooth. Happy modeling!

Hi!
I never had any problem with it in the harsh Caribbean climate. The only one that got yellow is the mono-urethane (a shade of brown, actually).
Beware that is very soft coat and the sanding / polishing can be a problem if you don't have a dehydrator. As said earlier, multiple coats work better (I've seen up to seven!), but if you want to stay in the acrylic neighborhood, I will strongly suggest Alclad Aqua Gloss instead.

Gabriel