Cal. Rev. & Tax. Code § 7307

“Blended motor vehicle fuel” means any mixture of motor vehicle fuel with respect to which tax has been imposed and any other liquid on which tax has not been imposed. Blended motor vehicle fuel also means any conversion of a liquid into motor vehicle fuel. “Conversion of a liquid into motor vehicle fuel” occurs when any liquid that is not included in the definition of motor vehicle fuel and that is outside the bulk transfer/terminal system is sold as motor vehicle fuel, delivered as motor vehicle fuel, or represented to be motor vehicle fuel.