Solid polymer fuel cell power systems are compared to spark ignition engine power systems for utility vehicle applications. Utility vehicles provide crew and payload transport and electrical power at work sites. The two power systems, both designed to satisfy an identical service, are compared on the basis of life cycle cost and fuel energy used. This approach attempts to minimize biases and allows technologies to be compared on a level playing field. Gasoline is the fuel for the spark ignition engines, while liquid hydrogen is used for the solid polymer fuel cell. The results show that spark ignition engine power systems have a lower life cycle cost than solid polymer fuel cell systems for technology available today. If the anticipated improvements to solid polymer fuel cell technologies are realized, by 2005, solid polymer fuel cell systems should provide the lowest life cycle cost for utility vehicles built to supply high work site power levels and short driving distances.