A little writeup after getting inspiration from the other thread on here.

1997 Audi A4 1.8Tq Avant:
- 313,000km without any major mechanical problems - just stuff that gets used up
- still on the original turbo, still pumping 0.6 bar

1999 Mercedes ML430:
- 400m: new gearbox (yes, after 400 metres from leaving the stealership!)
- various major mechanical fixes
- total engine rebuild at 120,000km
- the invoices for all the repairs were over €30,000

2000 BMW 330d sedan:
- many small problems
- turbo failed at 75,000km

2001 BMW X5 4.6IS:
- 220,000km: new gearbox (supposedly expected lifetime)
- many few minor glitches such as rusting foglamp cables, etc.
- AC failed 6 times or so
- basically can't go two weeks without a visit to the shop

2001 Audi S3:
- no problems, current mileage: 41.000km

2004 BMW 530dT:
- parking sensors still not working
- bluetooth not working since the car was purchased
- few minor electronic problems
- current mileage around 80,000km

2006 911 4S:
- no problems, 32,000km

2007 RS4 Avant:
- 10,000km and no problems so far


VAG seems a little bit more reliable as you can see.