are we talkin' big globs of it, or just a big hazy coating all over the vehicle?
Brittani's mom taught me a pretty neat trick one time... had that shit all over my car... not sure what kind of tree it was... anyhow, I thought I was gonna be clever, and use brake cleaner on the windshield (didn't care about the rest of the car, just wanted to see!)
didn't work for shit...
she takes a jug of lemon juice and goes about 3:1 water:lemon juice and gives me a bowl and a rag... cleaned that shit right off!!!!
Get a Clay Bar. I used "Clay Magic" It comes in a kit. The kit has the spray, pad, and actual clay bar. You spray on where it is, then clay it like you were waxing, and buff it out. It removes tar, paint overspray and all that shit. It worked great on mine. I had major paint overspray to the feel of sandpaper, and it took it right off. Make sure you put a coat of wax on afterwards too.