The 2018 BMW 640 Gran Coupe is available as a 4-door, 5-seat sedan. Starting at $81,400, the 2018 BMW 640 Gran Coupe RWD is powered by a 3.0L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 20-mpg in the city and 29-mpg on the highway. The top of the line 2018BMW640 Gran CoupeAWD , priced at $ 84,400 , is powered by a 3.0L , 6 - cylinder engine mated to an automatic transmission that returns an EPA estimated 19-mpg in the city and 28-mpg on the highway.