Yeah, the V6 diesels have timing chains, so that is one less service item.
What gearbox does this example have? Is is FWD or quattro? If its a FWD auto, I'd probably steer clear, as multitronics (i.e. continuously variable transmission) are plagued with problems and are expensive to fix, so I would avoid one if possible... especially on the torquey V6. I have a quattro tiptronic behind the 3.0 TDI, and it is pretty bulletproof. Manual box is probably fine as well.
Something to have a look for under the bonnet... if you yank the engine cover off (just pull upwards firmly, you can't break anything), look for play in the linkages on the intake flap motors. A common fault for these engines is that the ends of the links wear out, and the ECU has a tantrum when there is more than a bee's whisker of play in them. Not the end of the world, but worth knowing about so you can knock the price down a few hundred quid if they feel like they might need doing
See here for a visual and further info about the problem and the solution(s)
Audi V6 TDi 2.7 & 3.0 Inlet Manifold, Swirl Flap Repair Kit.
Lastly, I have also been bitten by the pipe running to the rear window washer splitting and leaking all over the stack of electronics (sat-nav DVD drive, amplifier, etc) in the passenger side of the boot. Give the rear washer a good long spray, and then pop the cover off that compartment and have a really good look for damp (and also old water stains that might indicate it has been wet in the past). I believe it can also split/leak in the front passenger foot-well and trash parts of the MMI system such as phone and bluetooth modules, etc, so check for any dampness in the carpets there too.
I think that covers the major things... hope you find a nice example. I love my A6 avant, and am really pleased I decided to suck it up and shell out for a nicely loaded Le Mans 3.0 ... if you're gonna do it, do it properly!
