Lacquer thinner or acetone should do it. Make sure it is a base coat/clear coat paint. If you do this on single stage paint you're going to not have fun...
Bounce sheets. Or any brand dryer sheet. They take pine tar,bugs,caked on carp off pretty easy so road tar isn't much of a stretch from pine tar....right?
Engine starting fluid(ether) may help. Isopropyl alcohol maybe.
Carb cleaner spray should help too.
Stoner Tarminator if you haven't tried that yet, it's just plain works as intended...on TAR, or when I run out of that, it's xylene/xylol mixed with mineral spirits (of course, I live in CA which banned xylene/xylol). If the tar is dried and hard, nothing is going to make it an easy quick fix.