AudiForums.com - Used 2012/13 A6

To the best of my knowledge there were only subtle feature differences, such as LED headlights becoming an option beyond the Prestige edition, introduction of start/stop engine functions, and a top-view camera system. Whether these are features you would specifically want might help you to decide between the model years. Some have suggested that MY2012 being the first of the current series, might have a few more bugs that were then worked out in MY2013, but nothing major. True Delta reliability analysis may echo this.

In terms of maintenance, depending on what vehicles you have owned before, maintenance costs may be higher in terms of higher quality fluids, more expensive parts, etc. If the vehicle still has CPO warranty, a couple of the service checks can be expensive. You can search for the model and years maintenance schedule online. Being able to do basic maintenance yourself would help to keep some of the costs down a bit. While I have been nervous myself about the relative reliability to performance ratio of a German vehicle relative to the Japanese brands I have driven, I believe good maintenance and driving habits should make the A6 a decent long term driver. If what you are looking at has the 3.0L supercharged engine, that power plant has a good reputation.

Least favorite is difficult, as I have just had my MY2012 for four-months, so I am still in the honeymoon phase ;-) however, I find the prorpriatary MMI/AMI system lacks connective flexibility of straight USB. Those model years come with the "blue" iPod/iPhone 4 30-pin style connector which doesn't put up cover art. You may need to replace the cable, and they are not cheap. Otherwise, just stream audio via Bluetooth if you can live without the visuals. If the car comes with the original firmware, you may need to update it to be more stable with modern phones.