I may be a little late here but Mayonnaise and a paper towel takes the tar right off. I've done this for years and will never buy special tar remover from the store.
Do not use Magic Eraser on your car. It is an abrasive and will ruin the surface. I believe I used kerosene one time. It was pretty smelly and not the nicest thing to deal with. There is probably a product in the automotive section of a hardware store specifically for this purpose. You need something to dissolve the tar, and most household cleaners are not made for this purpose.
There is a product called "Goof Off" that would probably take care of the problem. I'd be sure to wash it off completely afterwards. Another possible solution might be a Mr. Clean MagicEraser? Good luck!
We always use WD40 to clean off tar. Just spray, let it sit for a few minutes, and wipe with a dry cloth.
Don't spray while the auto is in the sun.
Never wash your car with household soaps such as Dawn. Go to the automotive store and buy some tar removal liquid and follow the directions.
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