Unfortunately, we don't ever get a perfect point of comparison in the video because host Steve Sutcliffe never does a full lap in anger with either of them to set a time. Instead, he focuses more on how the BMWs feel behind the wheel. Sutcliffe also admits midway through the clip that the i8's electric motor is out of juice to power the front axle's electric motor. That only leaves the hybrid with its 228-horsepower and 236-pound-feet-of-torque turbocharged three-cylinder to spin the rear wheels.
Still, Sutcliffe spends ample time explaining the benefits and downfalls of driving these coupes. See where his opinion falls between the M4 as the traditional German sports coupe and the i8 as the new-school hybrid in the video, above.