The 2016 Audi S8 is available as a 4-door, 5-seat sedan. Starting at $114,900, the 2016 Audi S8 4.0T is powered by a 4.0L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated 15-mpg in the city and 25-mpg on the highway. The top of the line 2016AudiS8Plus , priced at $ 114,900 , is powered by a 4.0L , 8 - cylinder engine that returns an EPA estimated 16-mpg in the city and 25-mpg on the highway.