The main motivation for the present work was the idea to project and build a car, with a hybrid source of power, based on an electric engine, a group of batteries and a source of energy that can be a combustion engine with an electric generator, a fuel-cell or other. The main use of this vehicle was on an urban circuit, but allowing it to make broader circuits. The purpose of this task was to select, with a sustained study, what are the solutions for the source of energy for that kind of vehicle, considering the environmental, energetic and economical perspectives. The main project idea was to make a hybrid vehicle, with a higher autonomy than a simple electric vehicle, with a lower consumption as possible, and as cleaner and quiet as an electric vehicle can be. With this idea in mind, the future user can have an economic vehicle, with lower pollution emissions which can be used also in other voyages, because it has higher autonomy and can be refuelled more easily. In order to achieve the objectives of this work, it was made a research about the life cycle impacts considering several possible energetic choices. Based in three different international studies it was tried to make the proper connection to the Portuguese reality. This involved the extrapolation of the results obtained for other possibilities not mentioned as, for instance, the impact of the electricity production, based in the Portuguese data. For the energetic analysis, several scenarios were made, based on the higher heating value of the different fuels possibilities and on the thermal efficiency of different technologic arrangements. It was made a consumption determination, and a comparative analysis could be done for the several hypotheses that were at stake. Assuming a typical urban vehicle, with places for four persons, and taking into account the actual vehicles reality, the determination of the fuel consumption of that kind of vehicle were made, with similar weight and dimensions characteristics. This evaluation gives the total energy necessary for a vehicle of this kind and the percentage of electric energy that can be saved and also the percentage that has to be used. This can give the quantity of energy that has to be produced to assure that the car can move in urban and extra-urban typical journeys. Considering the energy consumption and how much it costs and the market price for engines, it is possible to make an economical analysis for the several possibilities. Taken into account the several results obtained, for the different choices that were object of the present study, it could be concluded about the choice for better source of energy to generate electric energy for propulsion to the hybrid vehicle.