The mission of the US Department of Energy's Office of Transportation Technologies is to promote the development and deployment of transportation technologies that reduce US dependence on foreign oil, while helping to improve the nation's air quality and promoting US competitiveness. In support of this mission, DOE has directed the National Renewable Energy Laboratory to conduct projects to evaluate the performance and acceptability of alternative fuel vehicles. NREL has undertaken several fleet study projects, which seek to provide objective real-world fleet experiences with AFVs. For this type of study we collect, analyze, and report on operational, cost, emissions, and performance data from AFVs being driven in a fleet application. The primary purpose of such studies is to make real-world information on AFVs available to fleet managers and other potential AFV purchasers. For this project, data was collected from 13 passenger vans operating in the Boulder/Denver, Colorado area. The study vehicles were all 1999 Ford E-350 passenger vans based at SuperShuttle's Boulder location. Five of the vans were dedicated CNG, five were bi-fuel CNG/gasoline, and three were standard gasoline vans that were used for comparison.