The 2015 BMW Z4 is available as a 2-door, 2-seat convertible. Starting at $48,950, the 2015 BMW Z4 sDrive28i (M6) is powered by a 2.0L , 4 -cylinder engine mated to a manual transmission that returns an EPA estimated 22-mpg in the city and 34-mpg on the highway. The top of the line 2015BMWZ4sDrive35is (A7) , priced at $ 65,800 , is powered by a 3.0L , 6 - cylinder engine mated to an automatic transmission that returns an EPA estimated 17-mpg in the city and 24-mpg on the highway.