Sensorless fuel level and oil change indicators are provided in a range extender for an electric vehicle. The range extender includes an engine, and an electric generating device driven by the engine to generate electric power supplied to the vehicle. The fuel level is calculated based on the generated power. The oil change indicator indicates that the oil should be changed when the number of engine rotor revolutions exceeds a threshold value. The electric generating device may be a dynamoelectric machine coupled to the engine by a shaft to operate as a motor for starting the engine. In response to prescribed engine conditions, the dynamoelectric machine is switched to operate as a generator driven by the engine to generate the electric energy.