> Ok, but your though goes out the window when the 89 octane E10 is the SAME
price as the non-E10 87 octane at the other stations.
Not at all, if you were paying attention. If you were paying attention I
said if you have a supply of *any* grade/blend/brand of fuel which produces
4 MPG improvement for only $0.10/gallon extra then by all means stick with
what works. But don't go off believing that just because that fuel was
labeled 89 octane that the same results can be had with all 89 octane
Octane *rating* is not a measure of energy content because it says nothing
about the composition of the fuel, only its anti-knock properties. Octane
percentage is useful as an energy content measure but octane rating only
compares anti-knock properties to pure octane/heptane mixes.
If you can't burn the gas as long due to the low octane rating then the
efficiency of pulling the energy out of the gas goes down.
The low octane knock causes the engine control module to reduce the spark
advance and reduce the burn time.
That all translates to an effect on mpg which I believe is worth looking
Of course there are many variables here that the group is aptly spinning and
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