In the attempts to attain greater efficiency of mobility, based in the long-term on renewable energy sources, the efficiency of energy conversion in the vehicle remains an important issue. Polymer electrolyte membrane fuel cell technology has the potential to improve the efficiency of the powertrain for passenger vehicles above the level of present internal combustion engine solutions in relevant operation areas. Several questions need still to be solved to verify this potential superiority under the conditions of daily vehicle operation. Therefore, new materials have to be developed for improved component performance at lower cost and for more complicated environmental conditions. The effect of these specifications on the efficiency potential of the fuel cell system is open to debate. Another target is the performance of advanced powertrains based on internal combustion engines, which are in competition with the fuel cell system.