2017 BMW X4 M40i BASE PRICE: $47,600 for xDrive 28i; $59,250 for M40i. AS TESTED: $66,995. TYPE: Front-engine, all-wheel-drive, five-passenger, compact SUV. ENGINE: 3-liter, TwinPower turbocharged, direct injection, M Performance inline six cylinder with Double VANOS and Valvetronic. MILEAGE: 19 mpg (city), 26 mpg (highway). TOP SPEED: 150 mph. LENGTH: 184.3 inches. WHEELBASE: 110.6 inches.