Something I discovered about the E free fuel i found in Texas is that it’s still not 100% gasoline. Instead of Ethanol, they use isobutanol. It’s supposed to have similar energy content and is not hydroscopic like ethanol.
I had to ask the place for an SDS sheet to find out.
They will use whatever is the cheapest component to achieve the end results. I'm sure they use less of it in summer blends though. Winter blends we would use butane at max until we hit RVP limits. Good octane and was cheap.