I think the XJS is one of those rare examples of a car where the styling tweaks and facelifts it got over years actually made it better.
I can recall being with my auld feller in his XJS V12 in the late 70s when he was stopped by the dibble...who asked if they could look at the engine. Pater was happy to oblige.
I wouldn't want to own a car where you can rest your elbows on the roof.