Tins report describes the experimental procedure used to evaluate the effect of selected fuel components (butane, propane and propene) of liquefied petroleum gas (LPG) on both regulated and speciated exhaust emissions. A total of seven LPG fuels were tested on three different vehicles. FTP-75 emission tests were conducted on each fuel blend for all three vehicles. Full hydrocarbon and carbonyl speciation were included for at least one test on each fuel. In general, fuel composition effects on post catalyst emissions were overwhelmed by vehicle to vehicle differences. There was no clear indication that one fuel showed best emissions in all vehicles. Results also suggest some dependence upon initial LPG fuel system calibration. Data presented here may lend itself to further statistical analysis which is beyond the scope of this paper. These mixed results suggest that more research is needed to provide greater insight on the effect of LPG fuel components on vehicle emissions.