Propane autogas is the internationally recognized term for propane when used in on-road engines. It is an energy-rich gas chemically known as a C3H8, and sometimes referred to as liquefied petroleum gas or LPG. As an approved clean alternative fuel under the Clean Air Act of 1990, it qualifies as an alternative fuel eligible for various federal tax incentives and programs.
Vehicles fueled by propane first appeared as an on-road engine fuel in 1913. There are more than 27 million across the globe. Propane autogas is the leading alternative fuel and third most commonly used vehicle fuel in the United States, following gasoline and diesel.