Most of the time I can just use a dry rag and end up with perfectly clear glass. I haven't used anything more than a light spray of water (re-used an old empty Windex bottle) & a rag on my vehicles for over a decade and it's never let me down. It takes care of dust, finger prints and the snot-hieroglyphics left by my dog. May be my imagination, but it seems to attract less gunk than anything else I've ever used so I don't have to clean them as often. For interior glass, chemicals are highly overrated IMHO - save your money!