ive got a 2.5 v6 tdi engine on an 02 , had it 6 years now, done around 60,000 after having bought it on 60,000 so 120,000 in all. On the engine, i've had alternator and injection pump go on me in that time and I had the cambelt done on 75000. I'd say that is quite reasonable for a 8 year old car now. Still driving and pulling like the day I bought it. Obviously, any car that has not been properly maintained, and regularly serviced will give you big problems in the long run, but as long as you get a fully serviced one with history, and then give it new oil and filter every say 6000 miles, with fuel filter every 12000, and pollen filter every 18000 miles, I cannot see you having too much problems with this engine.