The 2014 BMW 640 is available as a 2-door, 4-seat coupe. Starting at $75,400, the 2014 BMW 640 RWD Coupe is powered by a 3.0L , 6 -cylinder engine mated to an automatic transmission that returns an EPA estimated 22-mpg in the city and 32-mpg on the highway. The top of the line 2014BMW640AWD Convertible , priced at $ 85,900 , 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.