Hybrid electric vehicles (HEVs) are more and more of interest in the present vehicle market, because of the relevant reduction both in the fuel consumption and in the CO2 emission, in particular for the urban utilization. Different architectures are possible and have been considered for the vehicle hybridization. The most convenient architecture is depending on the application itself. This paper deals with a design methodology based on an optimization scheme to make the selection among the consistent number of alternatives. Optimization-based control strategies play a central role in the design process of HEVs. In early design phases they allow the comparison of different HEV powertrain architectures, thus supporting the selection of an appropriate topology. Furthermore, they lay the foundations for the development of real-time optimal energy management strategies to be implemented in the HEV on-board control unit. Fuel economy and design efficiency can overall be enhanced in this way. This paper aims at providing a comprehensive review of different optimization-based energy management strategies for HEVs. An analysis of strength and drawbacks of each considered strategy is carried out based on different evaluation criteria such as global optimality, computational cost and uniformity of the powertrain operation. Finally, simulation results for a HEV powertrain from the industrial state-of-art validate the conceptual and methodological comments related to the analysed controllers