DPF filter failure @ 48,000 miles with the previous owner.
Both exhaust manifold flap motors failed @ 50,000 miles and at a cost of €1,100 + VAT + labour.
Bearing on the rear prop shaft failed @ 68,000 miles. VW wouldn't sell the bearing alone, only a new prop shaft @ €1,500 + VAT + labour.
Factory fitted detachable towbar was incredibly noisy when towing, and should have been replaced under warranty as it is a common fault on these. VW refused... so I never bothered as I rarely towed with it.
Four wheel drive system began giving trouble @ 85,000 miles... that's when I bailed out!
The Touareg was a vehicle I aspired to owning from the first time I saw one. I loved the looks, the comfort, the fantastic 3.0 V6 engine and its very high level of refinement.
However, it turned out to be the most disappointing vehicle I ever owned. It was incredibly unreliable. My one was spotless with a full VW service history, however I cannot remember a week of ownership where there was not something wrong. It was the only vehicle that ever left me on the side of the road.
It was also overly complex and had incredibly annoying quirks such as having to remove the bumper and headlight in order to replace a blown bulb (a 2 hour job; the manual recommends you take it to a main dealer to do this!). Replacing the battery required you to take out the passenger seat... the list goes on.
Overall it was laughably bad, but the poor level of service from VW was the low light for me. They had no problem asking for incredible sums to fix all of these problems.
I've met several Touareg owners since, and they all had bad experiences re reliability and running costs.