This Ethanol Fuel Blends specification covers the requirements for automotive fuel blends of ethanol and gasoline for use in ground vehicles equipped with flexible-fuel spark-ignition engines. Fuel produced to this specification contains 51 to 83 volume % ethanol. Hydrocarbon blendstocks for meeting ethanol fuel blends performance requirements are unleaded gasoline, gasoline blendstocks for oxygenate blending (BOBs), natural gasoline or other hydrocarbons in the gasoline boiling range. This fuel is for use in flexible-fuel vehicles. Ethanol Fuel Blends shall conform to the performance requirements prescribed and be visually free of sediment and suspended matter. The ethanol, methanol, gum, inorganic chloride, water, and copper contents and vapor pressure, acidity, and pHe shall be tested to meet the requirements prescribed.