A system consisting of an internal combustion engine (ICE) and an electric generator, as used in serial electric hybrid vehicles (EHV) or range-extended electric vehicles, is considered in this paper. The use of a torque controlled generator provides an additional actuating variable for the control of the ICE. In this way, the power of the ICE can be controlled without using throttle actuator while following nearly maximum efficiency trajectory. A simple control algorithm is proposed for this approach based on an inner speed and outer power control loop. The resulting system is simple, robust and efficient requiring less energy storage than the usual on/off control strategy for EHV. The proposed algorithm has been implemented in a prototype and validated experimentally.