The 2008 Audi A6 is available as a 4-door, 5-seat sedan. Starting at $42,950, the 2008 Audi A6 FrontTrak FrontTrak Sedan is powered by a 3.1L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 18-mpg in the city and 27-mpg on the highway. The top of the line 2008AudiA64.2 quattro Sedan , priced at $ 56,300 , is powered by a 4.2L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 16-mpg in the city and 23-mpg on the highway.