The 2021 Audi RS 6 Avant is available as a 4-door, 5-seat wagon. Starting at $109,000, the 2021 Audi RS 6 Avant 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 22-mpg on the highway.