The M139 is a turbocharged inline-four engine produced by Mercedes-Benz. It is the successor of the M133 engine. It is also the first four-cylinder engine by AMG to be specified with two outputs, to be assembled by hand using "one man, one engine" philosophy, and to be equipped with combined port and direct fuel injection system. At 310 kW (416 hp) on its introduction, M139 is the world's most powerful four-cylinder engine in serial production with specific output of 208 hp per litre or 104 hp per cylinder.

Mercedes-AMG GmbH, commonly known as AMG, is the high-performance subsidiary of Mercedes-Benz AG. AMG independently hires engineers and contracts with manufacturers to customize Mercedes-Benz AMG vehicles. The company has its headquarters in Affalterbach, Baden-Württemberg, Germany.