My other halfs Almera had really awful paintwork, it was the cheap red basecoat but it looked like the previous owner had lived near a tar pit. What some cars have just behind the wheels, this car had it all over!! I was going to resort to tar remover, but had heard bad reports about it being very harsh. And I wasn't overly convinced it was tar, it did seem embedded in the paint rather than just stuck to it. For example, using a thumbnail made no difference.
So I thought I'd buy a lump of clay and see if it could pull the tar out of the paintwork. And while it does take a VERY long time, it has done the job. The paintwork is smooth to the touch now, and will actually show up when it's been polished. OK, it's still the cheap nasty red paint that is used for bottom of the range cars, but at least it looks clean now!!