I didn't really want to push this thread into the topic of ethanol in general, but it is most certainly not welfare. There are no government payments or subsidies to support ethanol production, and there haven't been for many years. Efficiency in agriculture continues to improve every year. By the time you factor in all the fuel used to discover, drill, pump, store, transport, and process oil, you use a lot of energy producing gasoline, as well. On the energy side of the equation, a car running 30% ethanol is already more efficient CO2-wise than any Tesla or other electric car (for those who care about that sort of thing).
My family is more involved in the oil business than the agricultural business, so I'm very familiar with both sides of the debate. Ethanol is cheaper because it is cheaper to produce than petroleum gasoline, and thus more efficient.