The 2008 BMW M6 is available as a 2-door, 4-seat coupe. Starting at $106,100, the 2008 BMW M6 Convertible is powered by a 5.0L , 10 -cylinder engine mated to an automatic transmission that returns an EPA estimated 11-mpg in the city and 17-mpg on the highway. The top of the line 2008BMWM6Coupe , priced at $ 100,300 , is powered by a 5.0L , 10 - cylinder engine mated to an automatic transmission that returns an EPA estimated 11-mpg in the city and 17-mpg on the highway.