Any know engine issues that I should be lookn out for? I'm also considering the xjr. Thanks

 

The engine is pretty solid. It's the air suspension you have to watch out for. Read up in this forum and you'll learn a lot about it. Also see the FAQ.

 

And Corrosion spotting that can break out on panels, like, front of trunk lid, front bottom door corners, window frames.
Also check that if you have the HID headlights, that they come one and are steady and do not flash. Not a Jag problem but a HID issue with lights that are getting older now.
Oh, and the air suspension, but this is harder to check but certainly no errors.
Oh, and the suspension bushes, they can be worn more than other cars of the same age.