Permanent marker stains on most surfaces present a problem. When those stains are on your car's exterior paint you have the added difficulty of trying to remove the marker and not the paint. Commercial products made for removing permanent marker stains contain acetate. Using these products on your car's paint will result in damage to the finish. Supplies found in the home are a safer, less expensive alternative and will successfully complete the job.
Saturate a white cotton cloth with whole milk. Whole milk works to loosen the permanent ink stain without invading or corroding your car's paint.
Place the cotton cloth soaked in whole milk over the permanent marker stain on your car. Ask someone to keep the cloth from sliding off the car, if needed, until you complete the next step.
Soak a large terry cloth towel with cool water and place it on top of the cotton cloth soaked in milk. Anchor the large towel over the top of the car to prevent both towels from sliding off the car. The weight of the large, wet towel ensures the milk-soaked towel is making contact with the permanent marker stain.
Leave the towels over the permanent marker stain on your car's paint for at least four hours. Lift the towels and wipe the permanent marker stain with a clean towel to see if it lifts. Add more whole milk to the cotton cloth, if the stain persists, and leave the towels on the stain overnight.
Remove both the water and milk-soaked towels from your car. Dip a clean cloth in a cleansing mixture made of a few drops of dish washing detergent and warm water. Wash off the permanent marker stain and milk solution.
Rinse your car's paint with a clean cloth dampened with cool water. Dry the surface with another cloth.
Apply aerosol hairspray, liberally, to any remaining permanent marker stain. Buff the area with a clean cloth then wipe down with cool water on a clean cloth.
Allow children to use only washable markers if they must use markers in or around the car.
Take your car to a professional if you have extensive permanent marker stains on your car's paint.