From www.sacbee.com and their Car Czar:
Stop rubbing! You're most likely just smearing the stuff around. You need to use a cleaner that's specifically designed to remove tar and pitch. These do a wonderful job and are widely available at just about any auto parts store. The cleaners are typically oil based and leave the paint intact.
But if you're a cheapskate like me, there may be another option. I mean, why go buy a product from a store when a quick trip to the kitchen cupboard will do? What's that, you ask? Automotive products next to your breakfast cereal? You bet. It's not only my favorite condiment, but also a great remover of tar and pitch. Mayonnaise!
Try rubbing a little mayo on a sticky area with a clean soft cloth. You'll find that it works wonders. Afterwards, just clean up the residue with some car wash soap and water.
So remember, next time you need to clean, don't hold the mayo.
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your friendly research nerd, spazzdog