The base Z4 sDrive28is uses a turbocharged four-cylinder engine to score 22 mpg city, 34 mpg highway, and 26 mpg combined with the manual transmission. Opting for the eight-speed auto shaves 1 mpg from the highway rating, but leaves the others untouched.
With more power comes somewhat poorer gas mileage: the sDrive35i rates 19/26/21 mpg city/highway/combined with the manual transmission. Pick the dual-clutch seven-speed gearbox and those numbers fall to 17/24/20 mpg.
The sportiest model, the Z4 sDrive35is, also scores 17/24/20 mpg city/highway/combined.
Those looking to save some cash at the pump with their sport roadster will choose the turbo four-cylinder Z4 sDrive28i, and in our experience, real-world gas mileage easily matches, and occasionally exceeds, the EPA ratings.