Ah yes sorry forgot about this thread.
If you've decided on a Mk2, the following applies.
The Mk2 was produced from 1996 on a P until 2000 on an X plate, although many remained unsold and so are common on 2001 X and Y plates as well. There were 2 very minor revisions throughout its life all with subtle changes.
The first was in late 1998, so most S reg cars onwards and it's cars this old and newer you should look for. The interior colour combinations improved, you got a slightly nicer interior with chrome door handles etc etc but no big deal. Crucially, the engine also changed for the 'newer' Blacktop Zetec engine with 100k/10 year cambelt interval.
S, T and most V plate cars - you need a Ghia X. You will get:
Leather Interior
Heated seats
Electric Seats
Air Conditioning
Cruise Control
Onboard Computer
6 CD Changer
Heated front windscreen
16" Alloys
Exterior colour coding
Sunroof
The Ghia is, by comparison, a very poor spec and should be ignored on cars of this age.
The final revision was July 1999 onwards build - so SOME V plate cars, but ALL W and X reg cars. You can easily identify these because the B Pillar (Between the doors) is black not bodycoloured. Here, the Ghia X gained side airbags and Semi Automatic Temperature Control (Like Climate Control). But the Ghia improved as well - the Ghia gained cruise, computer, and many other Ghia X refinements meaning that, if you are not fussed about leather, its pretty much as good.
So what do you need to look out for?
Frankly they are very reliable cars - the key problem is suspension bush wear, they last 30k miles tops really, but even replacing the entire arm is only about 60-70 quid a side. Not much that breaks costs much to fix. Check the Air Con works - if it doesn't, don't beleive the sellers claim it 'just needs a regass' without checking further - the condensers can rust through and are comparatively expensive to replace at a few hundred quid minimum. Buy one with working AC.
Rust - unfortunately, it seems they do suffer at random from rust around the rear wheel arches. There seems to be no pattern - some do, some don't. I've seen plenty of P and R reg ones without a spot of rust but then some newer ones with it. My V plate Ghia X, lovingly cared for and looked after by myself, is now beginning to go on both wheel arches. Very dissapointing and a real shame. It's not structural its purely cosmetic but god it looks cruddy. A tidy Mk2 Mondeo still looks half respectable, so try and find one without rust.
Uneven tyre wear does not neccesarily mean it needs new bushes - what housemaster said is also spot on. Mk2 Mondeos are heavy on tyres anyway - I never got more than 10k out of a set of Eagle F1's and when my parents had a Mk2 LX from 6 months old that didnt seem to do more than 14-15k to a set of Eagle NCT5's.
Optional Extras? They were not many, infact there were pretty much only two that actually matter:
a) Satellite Navigation - its totally crap. It absolutely doesnt matter if it has this or not
b) Sports Appearance Pack - transforms the look of the car. Was an option on the Ghia X, it's the same bodykit you find on the ST24. Looks good.
You couldnt get stuff like Xenons etc.
So there we go. Buy a nice 2000 model, W or X plate, for the best spec.
If you can find more money and get close to £2k the Mk3 starts to become an option.