There is a sticker remover specifically made for automobiles that will remove residue 10x better than anything I've ever tried. I can't think of the name off the top of my head, but I'll go look for it in a moment.
EDIT: Nevermind, it is a specialty from honda motorsports apparently. I used to get free stuff from them all the time because I worked at a dealer last summer. Obviously not something you can just run out and get. Sorry...
To mainman: how large is your CPS2 collection now? I remember last time you posted it, I was amazed. (I think you had almost everything)