I've been trying to figure out my mileage using the 87 grade with 10 % ethanol and then going to the mid grade which contains no ethanol. When I switch to the medium grade, it only costs 10 cents more per gallon; so cost isn't much of a factor. The problem is that I live in Wisconsin so the weather is factoring into my miles per gallon; I believe more than the ethanol factor. Does anyone out there believe that you can increase your mpg by not using ethanol mixed gasoline, and if so, how much more per gallon?
You definitely can get more, but don't overpay for it. In theory, the difference should be just over 3%. Driver claims vary widely, but one more rigorous study came fairly close to the theoretical amount. Beware that changing octane at the same time could skew the results. In the old days, higher octane had slightly lower energy content, but there are so many undisclosed variables in play that consumer comparisons are fraught with uncertainty.
It is hard to come up with any reliable conclusion when testing cars as there are too many factors involved. Though, if you had some kind of a generator that runs on gas the test would be more reliable.
