The 2008 Audi S4 is available as a 4-door, 5-seat sedan. Starting at $49,610, the 2008 Audi S4 (M6) quattro Station Wagon is powered by a 4.2L , 8 -cylinder engine mated to a manual transmission that returns an EPA estimated 13-mpg in the city and 20-mpg on the highway. The top of the line 2008AudiS4(A6) quattro Sedan , priced at $ 49,710 , is powered by a 4.2L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 14-mpg in the city and 21-mpg on the highway.