BMWUSA updated their 2015 BMW M3/M4 minisite with the official US EPA figures. The 2015 BMW M3 and M4 with DCT has a rating of 17 MPG for city driving and 26 MPG highway. The same models with manual transmission are reportedly doing 24 MPG in highway driving.
BMW has reverted to an inline six cylinder for the new M3 and M4. But unlike the S54 in the E46 M3, the new S55 is turbocharged. Based on the N55 six cylinder, the S55 utilizes VANOS and Valvetronic as well as gasoline direct injection in the cylinder heads.
Unlike the N55′s twin-scroll single turbocharger, the S55 utilizes two turbochargers, one turbo per three cylinders.
The S55 is set to deliver 431 HP and 406 lb-ft of torque. To ensure that nothing untoward happens on the bottom end the S55 employs a forged steel crankshaft. The torque developed by the S55 is fully available from 1,850 to 5,500 RPM which leads one to believe that the turbos selected for use on the S55 are slightly larger than the ones employed on the N54 motor of yore.
The new powerplant also boasts excellent fuel consumption, with an improvement of more than 25 per cent over the previous model’s figures, while emissions are already EU6-compliant.