I second what Rich posted above. I have used Pledge on a few cars where I had concern about the decals. Usually Pattos or decals I printed at home. I brush one or two coats and let it dry a day or two and then do the usual clear lacquer on top of that. I usually like to use clear lacquer, but that can be a crap shoot sometimes. Usually light mist coats and then full coats later. Usually no problem with model kit decals and Indycals products.
I also use Pledge on my car interiors and the black plastic stuff on the outside. Usually two heavy coats applied with a cloth. No buffing or anything, but it leaves a glossy finish on your plastic dash, not for everybody.