The 2015 BMW M6 is available as a 2-door, 4-seat coupe. Starting at $111,900, the 2015 BMW M6 Coupe is powered by a 4.4L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated 14-mpg in the city and 20-mpg on the highway. The top of the line 2015BMWM6Convertible , priced at $ 118,200 , is powered by a 4.4L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 14-mpg in the city and 20-mpg on the highway.