This thread is a perfect example of how we as buyers are more motivated by the discount than the price. Comparably equiped A6's have a MSRP much less than a 5 series. A nice discount on a 5 brings it down to what an A6 lists for. The other thing that works for Audi is that they have among the best resale value in it's class. Not offering big discounts on new cars is the prime reason.
2012 BMW 550 M-Sport
2015 Audi A7 Prestige
2014 Lexus GS350---Wife's car
2013 BMW 1600 GT---2011 Kawasaki Ninja 1000---2012 Ducati Panigale