When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
'08 received improved software / tuning which was actually a GM backward compatible upgrade for '06 and '07. GM and tuners would load the '08 software into '06 and '07 cars, tuners would then start their improved tuning with the '08 calibrations.
'10 got a different TCM, '12 received improved software / tuning. '12-'13 are considered the best of the C6 version of the A6. The 2014 C7 version was greatly improved and is considered the best version of the A6.
In short: 06-09 controllers are interchangeable; 2010, 2011, and 2012 are each different and while there might be some similarities it is safest to treat them independently. YMMV on that part.