Yep, probably NOT simple road tar (mostly bitumen), which many cleaning products will remove. I got the following linked stuff on one quarter panel of my Mercedes a few years back when the wheel spit it onto the paint:
http://sealmaster.net/wp-content/uploads/2013/05/CrackMaster544.pdf
I had to use heat and kerosene to soften it enough to scrape off with a nylon blade. Then used rubbing compound on an orbital buffer to get the rest. It took several coats of paste wax and wool buffing to bring the finish back to almost new.
If somebody finds a better way, please post it in this thread.