California Codes, Business and Professions Code - BPC, Division 5 — Weights and Measures, Chapter 14 — Fuels and Lubricants, Article 1 — General Provisions, Section 13404

(a) The sale of compressed natural gas by persons who sell compressed natural gas at retail to the public for use only as a motor vehicle fuel, and who are exempted from public utility status by subdivision (f) of Section 216 of the Public Utilities Code, is a sale of a motor fuel for the purposes of this chapter.

(b) Compressed natural gas sold at retail to the public for use as a motor vehicle fuel shall be sold in a gasoline gallon equivalent that shall be equal to 126.67 cubic feet, or 5.66 pounds, of compressed natural gas, measured at the standard pressure and temperature, described in Section 8615 of the Revenue and Taxation Code.

(c) Liquefied natural gas sold at retail to the public for use as a motor vehicle fuel shall be sold in a diesel gallon equivalent that shall be equal to 6.06 pounds of liquefied natural gas.