+1...This stuff works wonders. Use it on my cars. Xylene is the main chemical I believe.
PS. A well respected body man in our area recomended this also.
WD40 works great on tar, being they are both petroleum based products, with side benefit that it smells better than kerosene. It also helps remove decals, labels, bumper stickers and the like, left over contact adhesives if you peel off paper backing.