The Texas Project: Part 1 - Emissions and Fuel Economy of Aftermarket CNG and LPG Conversions of Light-Duty Vehicles

The Texas Project is a multi-year study of the emissions and fuel economy of aftermarket conversions of light-duty vehicles, including passenger cars, light light-duty trucks, and heavy light-duty trucks. The test fleet, consisting of 86 mostly 1994 model year vehicles, includes eight different types of light-duty vehicles that have been converted to dual fueled operation for either CNG or LPG and corresponding gasoline controls. Virtually every type of aftermarket conversion technology (referred to as a “kit” for convenience) is represented in the test matrix: eight different CNG kits and seven different LPG kits, all of which have closed loop control systems. One goal of The Texas Project is to evaluate the different kits for each of the applications. One method used for evaluating the different kits was by assessing their potential for attaining LEV certification for each of the vehicle applications. For six of the eight vehicle types examined, at least one kit was identified that appears to have the potential for LEV certification. Finally, the fuel economy of each vehicle when operating on the alternative fuel was compared to that for gasoline operation. Although there were exceptions for specific vehicle/kit combinations, based upon a statistical analysis of the fuel economy data, it is concluded that the fuel economy when operating on either CNG or LPG is not statistically different from that when operating on gasoline (when both are expressed on the basis of miles-per-gallon of gasoline-equivalent).