An integrated mathematical tool is presented to simultaneously design powertrain and control strategies for PEM fuel cell hybrid vehicles. Such an activity is motivated by the positive impact of car electrification on transportation related GHG emissions, and by the potential of hydrogen as an intensive energy carrier to avoid heavy battery packs, as required for pure electric cars. Moreover, the availability of reliable and comprehensive mathematical tools is recognized as a key to develop cost effective and highly performing innovative powertrains. A database of hybridizing devices' costs and weights is developed and exploited in conjunction with a weight model to size the powertrain as a function of degree of hybridization. In parallel, a versatile heuristic control strategy is proposed to easily adapt control rules to different powertrains. Then, both the weight model and the heuristic control strategy are embedded into an optimization procedure to determine the most convenient PEM fuel cell hybrid vehicle configuration. The methodology is tested for a fuel cell hybrid shuttle, whose hydrogen feeding is guaranteed by a photovoltaic on-site generation system. Such a case study not only is suitable to assess the proposed optimization procedure, but also serves at indicating the most promising short-term applications of fuel cell hybrid vehicles.