The 2015 BMW X4, which debuted at the New York International Auto Show in late April, is based on the taller X3 SUV but has a silhouette similar to that of the X6 “Sport Activity Coupe”—a term coined by the German carmaker to connote the crossover SUV’s coupe-like curves and performance. The X4 is available with two high-performance engine options: The X4 xDrive35i variant includes BMW’s flagship TwinPower Turbo 6-cylinder engine, which offers 300 hp and 300 ft lbs of torque for a zero-to-60-mph time of 5.2 se…