Originally Posted By: John_Conrad
In my state of MO. The letter of the written rfs is important, and to my knowledge it is applied state wide.
The only fuel that "may" be E0 is 91 or higher octane. This fuel was given the status of "exempt", however if you read further into the rfs, it states that "exempt" means that it is left up to the individual seller of the product as to whether he wants to mix in the ethanol. So basically, just because the rfs has "exempted" the 91 or higher ocatane fuel, does not mean you are automatically getting E0 in all 91 or higher octane fuel in my state. The rfs states that if said seller is selling E0 fuel in that 91 or higher octane fuel in the state of MO, it must be posted on the pump.
I have posted before on this and have provided links to the material referncing my state. Once again I close with the usual comment on how this rfs can vary from state to state and how everyone should become familiar with how it is being met in your particular state.
From an economic point of view it makes the least amount of sense to make 91 octane without ethanol. Ethanol is an extremely effective octane booster. However, it really does depend on the demand for higher octane in a particular area. Around here, there's a high proportion of European, performance, forced induction, etc cars that spec at least 91 octane and sometimes 93 octane (R+M)/2 unleaded. We had so much demand that about 15 years ago the standard premium fuel in California went from 92 to 91.