Ethanol is more environmentally friendly than pertroleum. You can make it out of renewable products, potatoes, corn, beans, they are trying sugar kane right now. The only way gas is comparable is that it takes about the same amount of water to make a gallon of ethanol/gas. There are plenty of advancements in farming over the last 10 years to improve the amount of harvest/yield while still using less fuel in the process.
When you get fuel from the pump, they have to post the MINIMUM octane rating of the blend. The blend % differs from summer/winter depending on the area. The minimum octane rating posted on E85 is 105 octane. This doesn't mean that it's always 105 octane.
For the gas station to make the blends of ethanol at the pump, they take 87 octane fuel and blend it with E100-pure ethanol, which E100 is widely accepted as being 113 octane. Your 89 octane blend contains 90% 87 octane and 10% E100. The winter blend of E85 contains 70% E100 and 30% 87 octane fuel which rates it at 105 octane. The summer blend of E85 contains 85% E100 and 15% 87 octane fuel RATED AT 109 OCTANE. I usually get E85 for $2.00-2.20 a gallon.
Now, the common drawback is the poor gas mileage
with Ethanol. In the past few years, car manufacturers developing flex fuel vehicles started out with a 30% reduction in gas mileage when running E85. In the most recent years, those car now only see 10-15% percent reduction in gas mileage. The manufacturers are only starting to touch some of the key benefits of E85. Most of them (from clubgp experiences) is the amount of timing you can add without ill affects/knock on the car is huge. The other thing being that E85 has a relatively large range of air/fuel ratio that the car still makes power, it is more forgiving. The last thing being the cooler burn, some carburated racers who have converted notice a 20* drop in engine temp from the normal. Most boosted cars have noticed the ability to run more pounds of boost as well as more timing on E85 rather than 110 leaded fuel. Therefore if cars were to run a leaner AFR and max timing in cruise, you are able to recoup most of that gas mileage. If someone really tried, they probably would be able to get 30mpg on a grand prix without replacing the engine every year. Remember, $2.00 a gallon for pump gas 109 race fuel
There has also been some racers replacing Q16 with E85. In some classes, E85 is considered a power adder and not allowed.
