My "other" car before I bought my GTI was a Honda S2000, the facelift version with twin oval chromed tailpipes.
By virtue of their shape and location directly behind the rear wheels, these would not only become filthy in a very short space of time, but would also collect bits of tar, which would then attach to the hot exhaust.
The best way that I found to clean the tar and other crud from the tailpipes was as follows:
You will need some paper kitchen towels, two plastic bags, some rubber bands, a can of WD40 and a tube of Solvol Autosol. You may have guessed from the foregoing that the operation takes place on a cold exhaust.
WD40 will dissolve tar, but will evaporate. Wrap the kitchen towels around the tailpipes, then soak with WD40. Place the plastic bags over the tailpipes, secure with the rubber bands, and leave for an hour. After which most, if not all of the tar and other crud will easily wipe away. Clean off any residual WD40 and give the tailpipes a polish with the Solvol.