I'm also interested in an ST220 and wondering if you guys could provide some advice on a few points:
1) At What sort of mileage do these cars tend to show their age mechanically? I'd assume these cars spend most of their lives bombing down the motorway rather than crawling round town?
Depends entirely on how well they've been looked after and how they've been used. I'd expect them to have been used more for longer journeys like you said, however now that they're getting older and cheaper it's likely they've been driven hard, possibly even been used on track, etc., so make sure service history is present and plentiful. Common mechanical areas needing attention are rear subframe bushes (knocking and wobbly feel from the rear end), rear brake calipers (sticking), and handbrake cables (seizing). There's a few other little niggles but nothing really major or wallet-busting.
2) Recommend some good year round tyres (are they just called "summer"?)and how much do they cost / how long do they last? Or will I be committing a cardinal sin by getting a summer set?
Continental Sport Contact 5s. Excellent tyres in the wet, dry, cold, hot, whatever. Not so hot in the snow but I still managed. They're about £120 per corner.
3)What extras are generally a necessity for daily driving?
They're extremely well-equipped as standard - desirable optional extras are xenon headlamps, parking sensors, and sunroof. Some say sat nav too, but it's a bit ancient now and doesn't offer anything in the way of USB or iPod integration so I don't see the point.
4) Do ST220s come in both 5 and 6 speed manuals? Is there any reason why I should avoid either?
Only the pre-facelift models (up to the first half of 2003) are 5 speed. There's no need to buy one of these unless you can get it for £500 or something. There are numerous improvements with the facelift aside from the gearbox.
5) Can I get a decent (under 60k miles, preferably newer than 2004) ST220 for £5k?
Yes.
6) Is this a decent ST220?
http://www.autotrader.co.uk/classif...type/petrol/radius/60/price-to/5000?logcode=p
Looks nice and well-looked after, but then again adverts can be deceiving! It'll cost you £475 to tax though sadly (see below)
General question about tax- what band do these fall in and how much is a years tax both before and after 2006?
They cost £280 per year if they were registered before March 2006. After that, £475. It's utterly ridiculous But not the end of the world if, at the end of the day, you get the newest and nicest ST220 you can find!
Apologies for the question overload!