35+ years ago when I started my work-life at the full service swirl-o-matic car wash we used dry cleaning fluid for tar, cosmoline etc. Once the EPA stepped in and we could no longer get the stuff we used what the old-timers used... kerosene. I had a poorly prepped new car with cosmoline around the wheel wells and rockers as well as a lot of tar and was out of my normal grunge-melter. Had some kerosene in the corner of the garage and it still works fine.

rops:
Might not want to use it under the hood around things that get hot though. Stinks up the place and totally kills the suds in the wash bucket but it works in a pinch.
TL