I am the second owner of an 07' A6 4.2, have had it for about 2 1/2 months, bought it with 57k. Car feels much bigger/heavier than my 02' A4, as expected. I know about the DI motors, and their propensity for carbon build-up on intake valves, so have an idea what to watch for (mostly).
I've put about 3k on car so far.
The car starts easily, no observed mis-fires (hot or cold), idles very smooth, engine runs very strong, am very happy with car, and have a trusted, reliable mechanic who has serviced my 92' Jetta GLI and 02' A4 "forever".

Carbon build-up: Some of you may be aware of discussion on the VW patent (2005?), that has a long technical discussion about valves, reducing CB, etc, etc. Part of that technical read-out mentions driving the car at 3k+ rpm for something like 20 minutes to supposedly heat the valves up to a certain temp, that will supposedly help burn off CB.

So, since its the intake valves that carbon up, I'm not sure how intake valves will get to or maintain the same relative temp as the exhaust valves - relatively cold incoming air would be cooling those intake valves, so my simple mind questions VW's claim that doing the moderately higher rpm runs would have much effect. Any techy types care to comment?
I enjoy the forum, have read many many posts, and thank you all for the discussions which I have benefited from. thnx