The $1 less for ethanol 85% you cite must be a regional thing as it varies from 10 to 5close0 cents cheaper in Illinois depending on the price of regular. So no savings would be as much as you calculated under those circumstances. To know the truth, an average differential cost across the country would need to be known. Additionally, the cost of ethanol 85% is artificially reduced due to government subsidies of the production, and its use increases the cost of foodstuffs. Just like most "green" things, the final cost is much greater than advertised.