The 2020 BMW M8 is available as a 2-door, 4-seat coupe. Starting at $133,000, the 2020 BMW M8 Base Coupe is powered by a 4.4L , 8 -cylinder engine mated to an automatic transmission that returns an EPA estimated 15-mpg in the city and 21-mpg on the highway. The top of the line 2020BMWM8Competition Convertible , priced at $ 155,500 , is powered by a 4.4L , 8 - cylinder engine mated to an automatic transmission that returns an EPA estimated 15-mpg in the city and 21-mpg on the highway.