How do I remove spray paint overspray from car windows?

Overspray on glass usually needs mechanical removal, because mineral and water-spot removers are not designed to dissolve paint. A clay bar with plenty of lubricant removes most light overspray. On exterior glass, a new razor blade held flat with soapy water can lift stubborn dots, but keep it well away from tint, defroster lines, rubber seals and painted edges. A suitable solvent can soften some paints; test it first and keep it off surrounding paint and trim. Heavy overspray is best handled by a professional.