How about a little water and a toothbrush? I haven't come across this problem, but I am sure others may have!! I am sure they'll chime in to help you out!!
Believe it or not, but try peanut butter. Something about the oil combined with the "paste" of ground nuts has been known to work. A plus is that it is easy to spread and not get on the paint... Let it sit a while before you wipe it off. Might need a toothbrush to work it into teh texture, too. There are also some detailing products sold specifically for this (see Autopia.org boards), but they don't make as good of a sandwich...
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2008 GT Convertible in Dark Candy Apple Red Metallic with black cloth top and dark charcoal interior. 5-speed manual. 3.55 axle. Interior Upgrade package (woven Charcoal), Premier Trim, GT Appearance package, HID headlamps, and CS side scoops.