Power Split Hybrid Electric Vehicle (PS-HEV) the most efficient solution to reduce fuel consumption using electric hybridization of vehicles. However, different architectures exist or can be developed and it is difficult to perform a fair comparison between these solutions. A global design approach optimizing the size of the components and using optimal energy management can be a good way to compare different PS-HEV architectures. This paper presents a method to size and design HEV on an optimal manner and to compare this vehicle on different objectives; fuel consumption, battery size, global volume of the system. The method is then applied to four SP-HEV based on existing architectures (Toyota Hybrid system, Opel Ampera) and on alternative solutions (Electrical variable transmission, serial-parallel architecture).