Experiment all you want..... But if you want an inexpensive tried and true way to easily remove the tar from your vehicle without excessive harsh scrubbing, Take a quart bottle of Kerosene and mix a half ounce of carwash soap in it and go.
If you want to loosen all the things that have an adhesive base to it like say..... Your trim mouldings, mudflaps, pinstripes, emblems...I could go on...
Then I say go ahead and experiment
I'll run a thread on how to re-apply those things
Proper tool for the job!