A mechanical and electric drive train of a motor vehicle having an internal combustion engine and an electric motor, includes a conventional drive train which is driven by the internal combustion engine, an electric motor drive drain which is driven by an electric motor, a manual gearbox arranged in the conventional drive train, and at least one axle drive unit for driving axle drive members which are connected or are connectable via a clutch to driving wheels of at least one axle of the motor vehicle. The electric motor drive train is frictionally connected between the manual gearbox and the axle drive members to the drive train via at least one first clutch device, wherein the frictional connection can be produced and eliminated by actuation of the first clutch device.