Thirty years ago, I investigated Ethanol-spiked gasoline, at the time it was nicknamed "Gasohol" and there were many-many unsubstantiated claims. How much energy it saves depends upon how much energy is consumed in the growing of the crops (plowing, fertilizing, insecticides, etc.), harvesting them and process energy consumed in making the ethanol and transporting it to distribution/mixing locations. At that time, there were substantial questions about the "net" energy savings of ethanol. I have yet to see a good, unbiased neutral study of the topic. That lack, in-itself, tends to make be feel skeptical.