According to Chevron's pdf book, while ethanol may be used to boost octane, that was not the initial purpose of its introduction.
As of 2009
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The Super Premium my family generally used was American.
American (owned by Standard Oil of Indiana) never used lead in their highest octane motor gasoline.
"While most oil companies were switching to leaded gasolines en masse during the mid-to-late 1920s, American Oil chose to continue marketing its premium-grade "Amoco-Gas" (later Amoco Super-Premium) as a lead-free gasoline by using aromatics rather than tetraethyl lead to increase octane levels - decades before the environmental movement of the early 1970s led to more stringent auto emission controls which ultimately mandated the universal phase out of leaded gasoline. The "Amoco" lead-free gasoline was sold at American's stations in the eastern and southern U.S. alongside American Regular gasoline, which was a leaded fuel."
from AMOCO | Petroleum Equipment Institute
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saved from https://www.historicvehicle.org/vanishing-americana-roadside-business-edition/
Why methanol is not used is touched on in this sidebar on page 55 of the Chevron book
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