Liquefied petroleum gas (LPG), commonly called propane, is a mixture of at least 90 percent propane, 2.5 percent butane and higher hydrocarbons, and ethane and propylene make up the remaining balance. It is a byproduct of natural gas processing and/or petroleum refining.
A propane-powered vehicle can’t run as far on a tank of gas as a comparable gasoline-powered vehicle, but propane generates lower vehicle emissions. Propane emits 64 percent less reactive organic compounds, 20 percent less nitrogen oxide, and 20 percent less carbon monoxide than a similar gasoline vehicle.
Propane is a publicly accessible alternative fuel. There are fueling stations in all states. Today there are more than 270,000 on- and off-road, propane-powered vehicles in the United States.