> lowers the mean mpg… energy density And that's why we don't quantify energy efficiency using just MPG. You adjust for the density to get some sort of mile pe

> lowers the mean mpg… energy density And that's why we don't quantify energy efficiency using just MPG. You adjust for the density to get some sort of mile per gallon-energy-equivalent. > Making that energy less efficient I have no idea at all how this could happen, except to say that your very rough numbers do suggest a reduction in energy efficiency. EtOH is supposed to have 34% less energy per volume, so for E10 the reduction should be around 3.4% (IGNORING VOLUME CHANGES WHEN MIXING). This matches well with the "up to 2.8%" claim of Wikipedia citing[1], but certainly not what your engine is doing. [1]: https://web.archive.org/web/20070609142818/http://www.raa.net/page.asp?TerID=146 https://web.archive.org/web/20070609142818/http://www.raa.ne... > the fact that we're literally burning food We are all minions of corn. The hope has for a long time been on grass and other stalks full of waste cellulose digestible only by microbes in ruminants and fermentation plants, but these just keep on not delivering. Isobutanol was supposed to be a more gasoline-like biofuel too. Nobody figured out how to make it cheaply enough to burn either.