Autogas is the common name for liquified petroleum gas when it is used as a fuel in internal combustion engines in vehicles. The same equipment is also used for similar engines in stationary applications such as generators.
Autogas is widely used as a "green" fuel as it decreases exhaust emissions. In particular, it reduces CO2 emissions by around 20 percent compared to gasoline. It has an octane rating that is between 90 and 110 and an energy content that is between 25.5 megajoules per litre and 28.7 megajoules per litre depending upon the actual fuel composition.
In countries where gasoline is called petrol rather than gasoline, it is common for autogas to be simply referred to as gas. In the UK it is invariably referred to simply as LPG; the term "autogas" is never used, and "gas" in the context of automotive fuels is understood to be an Americanised usage for "petrol", not a reference to LPG.
In Asian countries, particularly those with historical American influences such as the Philippines, the term autogas is not commonly recognized as a generic term and the use of the term "LPG" or "autoLPG" is more widely used by consumers, especially by taxi drivers many of whom use converted vehicles. The converted vehicles are commonly called LGP vehicles or LPG cars.
Another source of confusion is that the term autogas is used in the United States to refer to automobile fuel, when used in piston-powered small aircraft. Aircraft owners using this fuel in place of the more common aviation fuel or avgas, require a Supplemental Type Certificate issued by the United States Federal Aviation Agency.
Toyota made a number of LPG-only engines in their 1970s M, R, and Y engine families. Currently, a number of automobile manufacturers—Citroën, Fiat, Ford, Hyundai, General Motors, Maruti Suzuki, Peugeot, Renault, Toyota and Volvo—have OEM bi-fuel models that will run equally well on both LPG and gasoline.
Vialli manufacture OEM LPG powered scooters and LPG powered mopeds that run equally well on LPG. Ford Australia has offered an LPG-only variant of their Falcon model since 2000.