California Codes, Business and Professions Code - BPC, Division 5 — Weights and Measures, Chapter 14 — Fuels and Lubricants, Article 5 — Standards for Spark-Ignition Fuels, Section 13440.5
For purposes of determining the percentage of ethanol in a gasoline-oxygenate blend for use as a fuel, the volume of ethanol includes the volume of any denaturant (including gasoline) that is added to the extent that these denaturants do not exceed the maximum volume percent specified in the latest standard established by ASTM International, except that no standard shall be less stringent than required by any California state law.
Notes
Defines ethanol volume, when determining the ethanol percentage in a gasoline-oxygenate fuel blend, to include any added denaturant, including gasoline, so long as the denaturant does not exceed the maximum volume percentage in the latest ASTM International standard. No applicable standard may be less stringent than California state law requires.
Use as reference
Lexinter.net | California Code, Business and Professions Code - BPC § 13440.5 | https://laws.lexinter.net/codes/california/business-and-professions-code/division-5/chapter-14/article-5/section-13440-5