I had to buy some saw gas (gas for a chainsaw), and since chainsaws get terrible indigestion on the new "corn squeezings" gasoline, a few stations locally sell non-ethanol premium (92 octane). The price is significantly higher. Just paid $4.25 a gallon for it, versus $3.59 for premium corn liquid. Since I was down to two blips on the gauge, had them fill the Prius with the non-ethanol stuff, also. Was getting 44.4 or 44.5 MPG. After the fill-up, was getting 45.1 or 45.2 MPG. Not a significant jump, and not worth the price difference, but interesting. Wonder if ethanol-laced premium, which is cheaper, gives any better MPG? Of course, one somewhat tank of fuel is no real proof of anything....
E-10 is known to have 3.3% less energy per gallon. That is what you are seeing. The price you are paying is really not worth it. Premium should not give you much, if any, increase in mileage. Generally. premium is only recommended if you are experiencing engine knock.
And it would be amazing if the MPG difference was really due only to the "E0". Most likely it was because the car had warmed up, or there had been a change in the weather.
Some cars, especially older cars from pre-ethanol era will get way better mpg on pure-gas... Also ethanol absorbs water so if you live in a really wet area like where I live there's less moisture getting into your engine. Of course if you have a rubber bladder for a gas tank like Gen2 owners there is very little opportunity for water to get in the tank in the first place. Some say ethanol is bad for some of the seals in the engine, but again, that's usually with older cars... The prius was designed to run on low-grade E-10... But where I live pure-gas is only 25 cents more a gallon so I prefer it! Here's the link to how to find ethanol free gas in your region: Ethanol-free gas stations in the U.S. and Canada
E-anything will get fewer mpgs due to it having less energy per unit measure. The more E, the less mpgs. Proven fact.
The only exception is if the increased octane of E-whatever allows the car to advance timing and/or lean out the mixture to the point where the increase in engine efficiency is greater than the drop in energy per gallon.
Regular unleaded gasoline, not labeled, no ethanol, will have less ethanol than mid-grade or premium, since ethanol is used to increase the octane number. Octane means that the molecule has 8 carbons in the chain. Septane and sextane molecules detonate at a lower temperature and causes "dieseling."
The laws are different in every state... Some states like California you can't buy gas at the pump without ethanol... The best way for me to avoid Ethanol gas is to use the website pure-gas: Ethanol-free gas stations in the U.S. and Canada
Here is a link...implication is not all states require ethanol labeling, incl. CA Ethanol Labeling Laws - State by State Guide.
