Two potential applications of fuel cell power plants in passenger cars: drive and auxiliary power units are presented. Then, specific constraints for fuel cell stack and power plants are evaluated for each application. After the description of the different fuel cell technologies, they are compared mainly at the stack level and power plant level if significant, depending on various criteria corresponding to the different vehicle applications. Finally, technologies of potential interest for use in vehicles are evaluated. Proton exchange membrane fuel cell (PEMFC), providing short starting and response times at the stack level seems the most suitable technology for drive application. In an auxiliary power unit application, the solid oxide fuel cell (SOFC), which allows easier operating with a traditional engine fuel because of simplified fuel processing and presents good performance, may find an application.