The missus' mums car got done over with paint by someone, so i got hold of some alcy wipes that we use at work (Halfrauds) when mixing paint.
Came up a treat, rubbed the paint of then washed away any residue from the wipes away with some soapy water straight after. Couldn't tell it had been painted.
If you pop into to your local halfords i'm sure they'd let you use some if you wanted to give it a go!