Ethanol Blend Mandate
All gasoline offered for sale at retail stations within the state must contain 10% ethanol (E10). This requirement is waived only if a distributor is unable to purchase ethanol or ethanol-blended gasoline at the same or lower price as unblended gasoline. Premium gasoline is exempt from this requirement. Ethanol is defined as fuel that is derived from an agricultural source and that meets ASTM Standard D4806.
(Reference Missouri Revised Statutes 414.255)