To meet the targets of sustainable development and greenhouse emission reduction of the future vehicles fleet, the automotive industry needs to deploy cost-competitive and efficient advanced energy conversion systems for the future commercial personal vehicles. The efficiency improvement needs induce to search new structured methodologies allowing the integration of the efficiency/cost vision for different vehicle energy technologies, in the earlier design stage of the new vehicles and their propulsion systems. The assessment of environmental impacts is also needed. In this context, the aim of this thesis is to develop a generic methodology for the design of the vehicle energy systems, which can consider on a holistic way, the â environomicâ criteria. To design and evaluate the competitiveness of energy integrated systems for vehicles, a systematic comparison including thermodynamic, economic and environmental considerations is required. This thesis presents the development of a systematic environomic optimization for vehicle energy systems. The efficiency, economic and environmental performances are assessed for different energy technology options and their integration in advanced vehicles powertrains. The performances indicators are compared and the trade-off are assessed to support decision making and to identify optimal energy systems configurations. The results from the energy integration studies reveal the potential of the combinations of different options of energy recovery and the integration of the energy services on the vehicle efficiency. The additional cost of the ORC installation is estimated to be 40 -55 â ¬/kW. The competitiveness and the trade-off of different advanced powertrains (electric, hybrid electric and hybrid pneumatic) are assessed and optimal design configurations are pointed out. It appears that different powertrain configurations are in competition for optimal mobility service depending on the selected environomic criteria.