A drive train is proposed for a motor vehicle which is driven by an internal combustion engine, having a single friction clutch which has an input element and an output element, wherein the input element is to be connected to a crankshaft of the internal combustion engine; a step-by-step variable speed transmission which has an input shaft connected to the output element of the friction clutch; and an electric machine which can be connected via a clutch to an output shaft of the step-by-step variable speed transmission in order to be able to apply traction force to the output shaft when the friction clutch is opened or closed, and which can be connected as a starter generator to the crankshaft in order to start the internal combustion engine or be driven by the internal combustion engine. The electric machine can be connected fixed in terms of rotation to the crankshaft while bypassing the friction clutch in order, in this way, to start the internal combustion engine when the friction clutch is opened or to be driven by the internal combustion engine.