Fuel includes any combustible gas or liquid, by whatever name the gas or liquid may be known or sold, of a kind used in an internal combustion engine for the generation of power to propel a motor vehicle on the highways, except fuel that is subject to the tax imposed by the Motor Vehicle Fuel License Tax Law and the Diesel Fuel Tax Law. For example, fuel includes, but is not limited to, liquefied petroleum gases, kerosene, distillate, stove oil, natural gas in liquid or gaseous form, and alcohol fuels. “Alcohol fuel” includes: ethanol (ethyl alcohol), methanol (methyl alcohol), or blends of gasoline and alcohol (including any denaturant) containing 15 percent, or less, gasoline by volume measured at 60 degrees Fahrenheit.

“Natural gas” means naturally occurring mixtures of hydrocarbon gases and vapors consisting principally of methane whether in gaseous or liquid form.

The taxable unit for compressed natural gas (gaseous form) is 100 cubic feet of gas measured at 14.73 pounds of pressure per square inch at 60 degrees Fahrenheit.

The taxable unit for liquid natural gas and other liquid fuels is the United States gallon, which is 231 cubic inches. To convert liters to gallons, the quantity of liters shall be multiplied by .26417 to determine the equivalent quantity in gallons. The resulting figure should be rounded to the nearest tenth of a gallon.