You are dealing with a car that is headed towards the Big 50 in age. While 'heroic methods' like Bon-Ami, razor blades and fine steel wool might help, the fact is that road grit, acid rain and just occasional cleaning of a dirty piece of glass may have taken their toll and etched the glass to the point that nothing will do more then a OK and temporary cleanup.A big claw hammer or large rock and a call to your insurance company will help (did I say that - that's insurance fraud!!). My long gone '97 pick up was like that - nothing helped permanently.