Significant research efforts have been invested in the automotive industry on alternative fuels and new hybrid electric powertrain in attempt to reduce carbon emissions from passenger cars. Fuel consumption of these hybrid powertrains strongly relies on the energy converter performance, the vehicle energetic needs, as well as on the energy management strategy deployed on-board. This thesis investigates the potential of new energy converters as substitute of actual internal combustion engine in automotive powertrain applications. Gas turbine systems is identified as potential energy converter for series hybrid electric vehicle (SHEV), as it offers many automotive intrinsic benefits such as multi-fuel capability, compactness, reduced number of moving parts, reduced noise and vibrations among others. An exergo-technological explicit analysis is conducted to identify the realistic GT-system thermodynamic configurations. A pre-design study have been carried out to identify the power to weight ratios of those systems. A SHEV model is developed and powertrain components are sized considering vehicle performance criteria. Energy consumption simulations are performed on the worldwide-harmonized light vehicles test cycle (WLTC), which account for the vehicle electric and thermal energy needs in addition to mechanical energy needs, using an innovative bi-level optimization method as energy management strategy. The intercooled regenerative reheat gas turbine (IRReGT) cycle is prioritized, offering higher efficiency and power density as well as reduced fuel consumption compared to the other investigated GT-systems. Also a dynamic model was developed and simulations were performed to account for the over fuel consumption during start-up transitory phases. Tests were also performed on some subsystems of the identified IRReGT-system. Results show improved fuel consumption with the IRReGT as auxiliary power unit (APU) compared to ICE. Consequently, the selected IRReGT-system presents a potential for implementation on futur SHEVs.