Ethanol decreases power and fuel economy when mixed into normal fuel, so I'm guessing it has something to do with your driving habits.

 

Ethanol actually raises the octane. When you get gas with ethanol they use less of other octane raising additives to maintain the octane at the same levels.

I have not been able to get ethanol free gas since the 90's so I can't comment on actual fuel mileage but in theory you should do better.

I would venture that the difference is going to be smaller than the normal variation due to driving variations.

 

Pure gasoline delivers more energy than with a fuel blended with ethanol and should deliver slightly better fuel mileage.

Studies have shown that ethanol blended fuel has about 30% less energy in it than the same volume of gasoline.

So a 10% ethanol blended fuel should have about 3% less energy than regular gasoline. And you should get about 3% less gas mileage.

The octane rating of a fuel is not going to give you more miles per gallon just improved performance.

Where did the dealership fill your vehicle up at? On your second tank did you use the same place, if not maybe you didn't necessarily get a top tier premium fuel.

 

The dealership filed up with conoco regular. I get non-ethanol at the co-op farm and feed store. I have used it for years in all my vehicles.
So what is a basic mpg and or hours per tank with normal driving? Maybe I am doing better then I thought.

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It got colder.

 

This.

People don't realize how much this makes a difference.

 

I thought cold fuel was better for performance and mileage?
Some race cars have cold fuel injection.

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Cold fuel is BETTER, because it reduces detonation, or rather, is less prone to detonation. The density of a liquid changes very little with temperature until it changes its state from liquid to gas.

What you are noticiing is a combination of factors.

Its just plain flat out colder, this means its taking longer to get the engine up to operating temperature. A cold engine doesn't burn fuel as efficiently, there is also increased friction from colder oil. So you have less performance, and it requires more effort to get the same power out of an engine. Many tunes also run richer when cold.

Also, being Winter now, many places have switched to a Winter blend of fuel, which has less BTUs/gallon. Less energy, more fuel used. The winter blends are designed to resist condensation in the fuel tank. In some places like Chicago with its "Special" local only blends its worse and we see increases in fuel prices because the factories have to produce the "special" blend in lower volumes leading to a higher unit price.

 

Colder fuel just means more fuel is injected due to it being more dense it equals more power less fuel milage.

If ethanol free fuel yields 3% better than E10 and your MPG avg 25 you should gain 9.3 miles per tank. At 28 mpg its only 10.416 miles per tank.

 

Humm well maybe it's normal. It just had my mind twisted for a bit.

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Cold means everything takes longer to warm up to proper operating temp. People typically idle longer to warm up the coolant

Engine and transmission fluids are thicker. Wheel bearings don't spin as easy. Basically the car has to work harder to drive and mpg suffers.

 

Well that sums it up

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