(a) As used in this Code section, the term "compressed natural gas" means a mixture of hydrocarbon gases and vapors, consisting principally of methane in gaseous form, that has been compressed for use as a motor fuel.

(b) Notwithstanding any provision contained in the National Bureau of Standards Handbook or any other national standard that may be adopted in this state by law or regulation, any dispensing device used to dispense compressed natural gas for use as a motor vehicle fuel may display the measurement of compressed natural gas in gallon equivalent units or fractions thereof and may compute the sales price of compressed natural gas according to such units or fractions thereof; provided, however, that such gallon equivalent shall contain not less than 110,000 British thermal units.