Hi James,
Theres's a lot on the net about these cars so make sure you do some digging. I got my S4 Avant earlier this year and spent a fair bit of time on research.
Valves that continue to rattle doesn't sound good so I'd be vary wary. They can (and do) suffer from timing chain (it's a chain on these, assuming it's a B6/B7, not a belt) rattle on startup (read all the horror stories about eating timing chain tensioners and decide whether to believe them or not). In a lot of cases this can be cured with an oil change, but I suspect that's merely masking things. I do understand that Audi say the S4 can rattle a bit on startup from cold but goes within a maximum of a couple of seconds, mine (at 95000 miles now) 'touch wood' doesn't rattle. BUT it's recommended by many that you don't stick to the long life service regime, if you do then at least change the oil and filter between services, and use as good an oil as you can (I like quite a few use Fuchs Titan Race Pro S from Opie Oils).
Make sure it's got a complete service history, walk away if only part history, and after that all the usual rules about a second hand cars apply. If it looks good and you go ahead and purchase then for peace of mind do an oil change as soon as you get it, then enjoy. Fortunately mine had Audi service history from new and had not been tampered with, but I did an oil change anyway.
I'm sure fuel economy isn't an issue if you're considering a 4.2 V8 but autos are slightly better due to their gearing (mine's an auto and I'm averaging 24mpg with a real mix of driving).
Broken glove box, no problems - get a 'repair kit' which is a couple of bent brackets from eBay and the problem is sorted. I got mine from a guy in Cyprus of all places (IIRC) and it cost a couple of quid. If it's got sat nav then latest discs can be had off eBay if you're in the right place at the right time, avoid the ones offering 7 digit postcode search as they don't work, in my experience anyway, just go OEM.
This is my first post too! Hope the search goes well, you won't be disappointed if you find a good one.
Cheers,
Rich
