Don't get Teutonic Tamer started on that topic...
Things to look out for would be normal maintenance stuff like oil, plugs, filters etc. Make sure the car has service history, preferably from a main dealer for the first few years.
- These engines can suffer from sludging up and the oil pumps can go, leaving you footing the bill for a new engine in most cases.
- The 1.8T engines regularly suffer from failing coilpacks, which cause the car to run on less than the normal four cylinders. If a coilpack is ******** the car will shake violently and will struggle to go anywhere.
- The temperature sender also goes on these cars, causing the temp gauge to move erratically. ie it will move to 70c then, go back down to 0c and then back up again.
- There is a coolant flange (I know, I know) which is at the back of the engine which is known to leak coolant.
- The MAF can sometimes be past its best on higher mileage cars. A bad MAF will cause all manner of problems, such as lumpy idle, bad fuel economy, stalling at low revs, sluggish performance, flat spots etc.
Apart from that, these cars are generally reliable enough, just make sure you look around and don't get a thrashed one because it was cheap, there are plenty of A4's available.
I have the AVJ engine, there's nothing wrong with it. I've had it remapped and done a few bits and bobs which has improved the driveability no end. The standard K03 turbo is pretty lame though, it dies after 5500 RPM.
Oh, and in factory spec 150bhp or 163bhp it will be painfully slow!