Miss. Code Ann. § 75-27-114

Notwithstanding any provision within this chapter to the contrary, natural gas motor fuels shall be sold as follows: (a) Liquefied natural gas motor fuel shall be sold in diesel gallon equivalents defined as 6.06 pounds of liquefied natural gas; provided, however, that if the National Conference of Weights and Measures establishes a different definition of diesel gallon equivalent, such definition shall be used. (b) Compressed natural gas motor fuel shall be sold in gasoline gallon equivalents. A gasoline gallon equivalent of CNG shall be defined as 5.660 pounds; provided, however, that if the National Conference on Weights and Measures establishes a different definition of gasoline gallon equivalent, such definition shall be used.