No - you really can't change the tint/color without needing to paint the door jambs and then you're into a whole other level of cost. First find out what you've got - you may not have a clearcoated car. A non-metallic 300SEL from the late 80's may not be clearcoated. A $3000 paint job may be "worthy of a 300SEL" but it's not an economic proposition. Unless the car has some great sentimental value I would question the wisdom of such an expenditure. Virtually anything you get is going to be a catalyzed paint - that is it will be chemically hardening, not air dryed - it will be as hard as it will ever get within days. The best way " to be on top of the deal" is to go the book store (or library) and get a book on painting a car - $15 to $20.