The 2015 Audi A6 is available as a 4-door, 5-seat sedan. Starting at $46,900, the 2015 Audi A6 2.0T quattro Sedan is powered by a 2.0L , 4 -cylinder engine mated to an automatic transmission that returns an EPA estimated 20-mpg in the city and 29-mpg on the highway. The top of the line 2015AudiA6FrontTrak FrontTrak Sedan , priced at $ 44,800 , is powered by a 2.0L , 4 - cylinder engine mated to an automatic transmission that returns an EPA estimated 25-mpg in the city and 33-mpg on the highway.