Tailpipe soot from Hell
Yes, the soot on the tailpipes of this car is of a particularly insidious and tenacious nature. More like black ceramic than soot. The best advice i've seen on this subject is to wipe the pipe tips off once a week with a paper towel and some windex or whatever. Once that stuff sets up on there, after a few weeks, you'll need to chip it off with an axe (kidding, about the axe). I let the stuff sit on there for a month or two during the winter, and I tried all of the mentioned cures without effect. I ended up using chrome polish and extrordinary amounts of elbow grease to slowly wear that stuff mostly off and it really microscratched the finish on them.
I don't know if they are polished stainless or chrome plated. I worry about wearing off the chrome with too much scrubbing and these shiney tips are not like other cars. They are not replaceable. they are permanently welded to the exhaust system.
When it gets warmer I will try with polish and a felt polishing wheel on my Dremel tool and see if that smooths and cleans them. Meanwhile keep on wiping them off before the soot gets too thick.