Originally Posted by crosscats

Tyres are tricky - folks put on what they can afford and if you're not into pushing the car to its limits, cheaper tyres are kind of OK, as long as they're not total rubbish but this could open a real off-topic hornet's nest so best steer clear!
Under £4k was a good deal for a 35k '04 - but there will be others!
Given that the used car market seems to be driven primarily by vehicle age, in the fist instance (up to a point), my rule of thumb on XF values - FWIW - is that currently, given good all-round condition, non-curbed wheels, decent tyres, clean interior, preferably some tax & MOT and a low-ish mileage (sub-50k is my preference), an '04-plate is worth approx £4k, a '54 £4.5, an '05 £5k and so on... (For SRT6 add approx. 30-40% - but that's a different animal).
Obviously, a lower mileage and stonking good condition gives further 'Brownie points' in up to £500 increments, so a really cracking early '04 with, say 25k could be up to about £5 - 5.5k - but, for me, it would have to be REALLY good.
Fewer previous owners and service history help, too but you know that - it's basic used car stuff.

I've never worked out if auto or manual makes much difference - personal preference I guess but a cedar (red) interior could also add some rarity value - if that's what you want - not everyone's cup of tea.
Best colour is black (except for cleaning) followed by graphite ('machine' grey?), red, aero blue then SSB - but now I'm getting really personal and inviting trouble!