The concern with E85 isn't that it's not "clean", it's the alcohol/ethanol used to formulate E85.
But, seems tuners have and are using it with no ill effects.
Still, BMW recommends using no more than 10% ethanol mixed fuel.
E85 is 85% ethanol and 15% gasoline.
Time and mileage will tell if the alcohol has any damaging effects.
Alcohol has a greater cooling effect in the combustion chamber and that results in a higher octane rating.
But, it also has a less thermal energy, which will lower MPG.
Initial cost per gallon may be less, but overall you'll spend more by needing more E85 to cover the same mileage as regular gasoline.
Here is a good article/experiment showing the MPG differences and costs associated with using E85.
The power/accel tests in this article don't really translate directly, but I post this article for the MPG question not power performance comparison.
http://www.edmunds.com/fuel-economy/...ison-test.html
Some people will say there is not point to E85 as it costs more to operate and doesn't save much on emissions.
BUT, the biggest thing to remember about E85 is that it is a RENEWABLE fuel resource, meaning, we have ways to produce more over the long haul compared to the limited amount of oil available. Once we run out of oil we're out of gasoline too.
At that point E85 will look real good, unless we're mostly in electric cars by then.
