Acronym for "liquefied petroleum gas" or bottled gas or a mixture of butane and propane . In Canada, propane is the recognized term, not LPG as used in the U.S.A. Volatile petroleum gases are compressed to a liquid form. It must be kept under pressure or at a low temperature to keep it in a liquid form. It is generally less expensive than gasoline yet has high octane. It also does not create as much carbon deposit in the engine or dilute engine oil as gasoline does thus reducing the need to change spark plugs and other components as frequently. However, if not serviced and maintained properly, it can result in leakage and possible explosion . Most underground parking facilities will not accept propane powered vehicles.