Hybrid electric vehicles are currently considered a viable solution for fossil fuel saving and pollutant emissions reduction in transportation sector. The typical configuration of a hybrid electric propulsion system contains a reciprocating internal combustion engine – gasoline or diesel. Aiming to increase performance and to reduce pollution in road transport, a hybrid electric propulsion system based on a micro gas and steam turbine system operating with compressed natural gas is proposed in the paper. The micro gas turbine has a recuperative heat exchanger and the steam cycle has one pressure level. The study analysed the performance of the proposed system as a function of gas turbine engine pressure ratio and temperature difference of the gas turbine engine heat exchanger. Results indicate that, at equal power, the analysed system is more performant than internal combustion engines currently used in hybrid electric propulsion, so they could represent a viable solution in this field.