My paternal grandfather is on his 2nd XJ8, he owned of of the last bodystyle and then traded in for the newest version after they came out. Both have had strange problems and the nav system in the new one keeps failing. An uncle owns the newest XJR, it's the 2nd one he's had in just over 2 years. The first one was in the shop more than 40 times for various repairs and he had to sue them to replace it when it simply stopped running. The new one seems OK so far except for a rim that seemed to bend itself for no reason.
An aunt recently decided to purchase an S-Type V8, which is ugly but seems fine otherwise. Although I'd venture to say that the fact that it's essentially a Lincoln LS with a different body has something to do with that.