time to get myself shot..... My vote is actually a VXR8 with LPG,
BUT
just as an alternative
a late model 3.0 X type jag estate.... pref with a manual box.
it WILL require frequent servicing, keeping a close eye on the transfer box (usual cause of failure seems to be being allowed to leak, as they only hold 0.5l of fluid, it doesn't take long to run dry, which kills it quick... as you'd expect ) , and coolant system... and rust on the sills, , but at least it's a fairly std diagnostics port.... (checked mine out the other day with a mate's cheapo USB reader and lappie)
but..... bloody hell they're fun to drive..... seriously, I actually prefer "the drive" in my 2.5 Jag to the 3.2 Mv6 , although the mv6 is markedly quicker (thus my suggestion of the 3.0)
there are a number of issues to be aware of.... but seriously, the chassis is a rather beaut of a drive.... i'd let you have a go in mine but i know you'd kill my third gear ,
as for comfort..... some say they're cramped, but i'm bigger than you and i don't find it so..... there's no excess space, granted, but there is sufficient even for a 6ft+ 20 stone grizzly bear... what's more, long distances no problems, i did arbroath to berinsfield in 6 hours 25 minutes, a couple of weeks ago, after a three day scottish wedding do...... and felt fine when i got home.... and as you well know, my spine is at least as knackered as yours, possibly worse.....
the estate is wayyy prettier than the saloon, and has excellent boot space for the class, not as cavernous as the omega, but enough to be very useful
there's a rather good educational article here
http://www.aronline.co.uk/blogs/cars/jaguar/x-type-jaguar/the-cars-jaguar-x-type/a late (post 2005) model with all the trimmings will have all the toys you want, and some..... the AWD system drive feels like a really good RWD , with infinite grip.... it's lovely to chuck around tight B/unlisted roads..... really precise, and goes where you tell it, when you tell it, i LOVE it.... it's made me enjoy
"DRIVING" again,
i've been driving V6 Omegas for 12 years , with 3 years of a v6 sintra before that, which itself followed more than 13 years of straight 6 senators ..
and i LOVE this Jag.
nuff said.
(Oh and the user forum is so far quite friendly and helpful, although perhaps not as technically rigorous as OOF can be.... )