Official
fuel economy figures for the standard M4
stand at 32.1 mpg, with CO2 emissions coming in at 204g / km; the CS produces 33.6 mpg and 197g / km of CO2 and the high - performance M4 GTS emits 199g / km of CO2 and returns 34mpg, but it's unlikely you'll ever achieve if you're driving it in the way it was intended.