I use "goo be gone". I use just a little bit on a cloth and don't rub too hard as I'm always afraid of rubbing through the paint - but haven't yet. It always cleans it off nicely. I will then usually take a mildly soapy rag and wipe it down afterwards just to remove the potent smell. Good luck.
X2 on the Goo Gone. Just cleaned my yellow panels up with it. Works pretty darn good. I rubbed fairly hard and used a good amount on the rag i had and nothing happened to the color. Works good.