Ethanol price dropped a couple of dimes in recent days on higher inventory news. So it's not just that, when corn prices plummet, as they have this summer in anticipation of great harvest, then ethanol prices come down, too. The fall of ethanol to $1.79 today (for Oct contract) is mostly related to the inventory news. But at this cheap price, it becomes even more "in demand" for refineries here in USA and the foreign market will step up demand, too.
The "cheapest molecule in the gas-tank" just got much cheaper. It should move back up a bit on new, extra demand.