With current engine designs, E85 will yield lower fuel mileage......but that's about to change. With the introduction of some of the newer engines with the 2013 cars/trucks, you'll see that playing field leveled a lot. The issue with ethanol has always been it's lower BTU rating, less energy per gallon. But it has one characteristic which makes it more usable and that's it's octane rating, it's higher than most gasoline. This allows the engine makers to do several things. Raising combustion ratios allows us to extract more energy from a fuel. Take GM engines that are coming out, they will have at minimum 11:1 compression with most at 11.5:1. That's considerably higher than the usual 8:1 a lot of the current engine have. So we will be able to extract more energy output of the fuel with the newer designs. Another benefit of the higher octane rating is we can now run more advanced timing. This yields 2 things- better extraction of the energy and cooler combustion temps which lowers emissions. Add the direct injection which allows us to run the engine rich when needed or lean saving fuel. The GM engines are also variable displacement. The 6.2 V8 which can make over 600HP but in small displacement mode is a 3.1 V4. In this mode, GM claims a fuel mileage in excess of 26 MPGs in the Vette. If they reduce the power output to more reasonable HP, they could get these kind of figures from a Silverado. The down side, once we embark on this road, we won't be able to go back. Ethanol will become a must fuel as the typical 100% gasoline fuel will cause detonation and the engine won't last long. My personal opinion, I think this is a mistake using a food source for a fuel when there is already so much world hunger. All we eed is a bad growing season and things will get dicey quick. WE have the technology to make clean headless engines that get HUGE fuel savings and make tremendous HP but you can't have it. Volkswagen is working on one now that should see the streets in Europe in the next 2 years. But because of politics, I doubt you see any here. Just like you don't see any of the BMW diesel sedans that get almost 90 mpg in Europe. It's all about the politics.
Sorry but unless you change the laws of physics, E85 will never come near the mileage of gasoline-period.
A mumber of vehicles already have compression ratios of 11:1 with many in the 10:1 range and have for many years.
You are falling for the sales hype car companies are using to pass off vehicles that do not have the towing, load, or passenger capacity of vehicles that the car companies have stopped selling so they can sell the fwd crap-wagon econo-boxes whildy telling the ignorant public that blown four bangers will do everything V-8s can can do and won't cost any more dollars in up-keep.
Of course they ignore basic facts that for a smaller engine to do the work of a larger one it is far, far, far more heavily stressed, therefore; it will have operational problems years to decades earlier than a push-rod V-8.
Most V-8s lope around no more that a couple of thousand RPMs over idle. Less strain means long life. Four bangers and even sixes work far, far harder to try to achieve similar performance the V-8s achieve.
And for those who are enamored with blowers (turbos) if you have access to a mechanics base rate repair book, compare similar tasks on a blown verses unblown engine.
As my local private garage tells me, with many of the newer cars, not far out of warranty, they tell the owners go to the dealer, by the time we remove all the junk under the hood to do the simple repair, we will have to charge you almost as much as the dealer does.
E85 is a fools folly foisted on an ignorant public by the government officials who probably know less about how cars run than the average woman.