I had to remove tar from my carpet a few months ago.  I just happen to
have a large supply of liquid nitrogen at my disposal- so i used it.  It
worked OK.  The big globs quickly froze and were picked off, but the small
stuff that was in the fibers required some organic solvents. I probably
used methanol (just because we have oodles of MeOH), but i'd speculate
Acetone or possibly methlene choloride would work too.

If you are in the greater palouse area and need some LN2 to remove some
tar, just email....
Cheers!
Matthew
ps, LN2 is about -200degreesC or 77K

Matthew Pollard             http://www.uidaho.edu/~poll7356
Dept. of Chemistry               http://www.chem.uidaho.edu
University of Idaho                   http://www.uidaho.edu