A drive-train system of a vehicle having at least one internal combustion engine, which may be started using an electric machine able to be coupled thereto via a clutch and controllable via an engine-speed controller. A control value of the engine-speed controller is detected toward the end of at least one startup operation of the internal combustion engine while the clutch is still subject to slip, and a comparison of the control value with a setpoint value is used to determine a value deviation, which is able to be compensated with the aid of a correction value in a renewed startup operation. Furthermore, a corresponding method is also described.