1. (a) Gasoline or gasoline blended with ethanol that is sold or offered for sale in this state during periods when areas within this state on either side of the meridian of 99° 00' west longitude line on opposite sides of the line have different volatility classes under the most recently adopted Schedule of U.S. Seasonal and Geographic Volatility Classes in ASTM International's publication D4814, "Standard Specification for Automotive Spark-Ignition Engine Fuel," conforms with this chapter and commission rules if it complies with the volatility class for either area.
2. (b) Gasoline sold or offered for sale in this state conforms with the Driveability Index provided in the Vapor Pressure and Distillation Class Requirements in the most recently adopted version of ASTM International's publication D4814, "Standard Specification for Automotive Spark-Ignition Engine Fuel," if it meets or exceeds vapor pressure and distillation class AAA, AA, or A.
3. (c) Gasoline blended with up to 15 volume percent ethanol is granted a vapor pressure tolerance waiver of 1.0 pound per square inch except for gasoline blends sold or offered for sale beginning May 1 and ending October 1 each year in counties required to comply with low emissions motor fuel standards.
4. (d) Seasonal specifications for vapor pressure may be extended for a maximum period of 15 days to allow for the distribution of existing stocks. New stocks of a higher volatility classification may not be offered for retail sale in this state before the effective date of the higher volatility classification.
5. (e) The vapor-to-liquid ratio specification under this section does not apply to gasoline or gasoline ethanol blends.
6. (f) This section may not be construed to interfere with regulations for low emissions motor fuels adopted by this state to comply with federal law.

Added by Acts 2025, 89th Leg., R.S., Ch. 950 (H.B. 4690), Sec. 6, eff. June 20, 2025.