Some of the older Audi/VW Turbo engines have an inherent flaw with the oil pump pickup. The mesh filter in the pickup would get clogged when the oil gets dirty from infrequent oil changes, clogged/broken PCV systems or using the wrong oil. I have read up about this and some guys who've dealt with these engines alot said it is good practice to service and clean the sump and replace the oil pump pickup tube with every major (cambelt) service. This also explains the early turbo failures since the turbo's one these cars are oil cooled and oil starvation would surely damage the turbo gradually.
http://www.audi-sport.net/xf/threads/2-0-tfsi-pick-up-pipe-clarification.227639/
I've had an engine failure on my 2004 A4 1.8T which cost me a pretty penny so I took it upon myself to figure out what went wrong to make sure it doesn't happen again. From what I found it all started with a faulty PCV valve (which cost R350 to replace) and a faulty thermostat which wouldn't let the engine heat up to the proper operating temperature. That caused the engine oil to become contaminated and clogged the oil pickup... And from there it was downhill.
If you buy the car my advice would be to do a full PCV system refresh and get the oil pickup replaced ASAP just for peace of mind.
Get the engine code of the car then check
HERE which oil pump/pickup and PCV system is running on that engine. You can also import the complete PCV refresh kits from
ECS Tuning
The control arms, or the bushings at least, on the Audi B6/B7 chassis also deteriorate after some time so I'll get those checked also.
Those are the biggest mechanical issues i can think of now.
As a 1.8T owner I would say that these cars are not for everyone, you need good knowledge of the car and it's flaws so you can do preventative maintenance on components that are known to fail. The plus side is that these are very popular with the VW/Audi enthusiasts so you'll always be able to get parts and there is a wealth of knowledge online for these cars. You can also get a diagnostic tool like VCDS to read error codes yourself, Google it, and then give the workshops specific instructions as per what you read.
They are very comfortable and has all the luxuries you need in a car, all in all very rewarding if you maintain them properly. Doing the aftermarket software and downpipe also make them quite sporty if you are so inclined.
If you plan to buy this and then trade it in for something else in a couple of years time it's probably not the best buy. I'm married to mine and won't be selling her ever, I spoil her with the best