The BMW M4 is a high-performance version of the BMW 4 Series automobile developed by BMW's motorsport division, BMW M, that has been built since 2014. As part of the renumbering that splits the coupé and convertible variants of the 3 Series into the 4 Series, the M4 replaced those variants of the BMW M3. Upgrades over the standard BMW 4 Series include an upgraded engine, suspension, exhaust system, brakes and weight reduction measures including increased use of carbon fiber, such as on the roof of the car.