So long as it is Top Tier, or if you're using an additive regularly if you're not using Top Tier fuels (the detergent content is key here), should be fine to use.

Ethanol has been blamed for creating gum and buildup, and too much of it in fuel will cause adverse engine behavior. But most cars run fine with up to 10% content.

The Owner Manual will specify that E85 and high ethanol content fuels are not recommended and will void warranty. Non-ethanol fuel should not be an issue.

 

If they sold ethanol free gas with better availability and competitive pricing then nobody would want ethanol diluted junk. Most cars are not built to run on gas with more than 10% ethanol as it's damaging to engines in high concentrations.

 

You'll want to calculate MPG at the pump to reduce error as much as you can and assess it then. (Some things we can't account for, but the margin of error in the computer can be sizable)

For a while, I thought if the price difference was within 10% I'd go for it but it was from the computer readout from an Elantra, so not really that scientific. I'll try again sometime now that I've been tracking fuel economy for a while.

 

If you said what were your start and end points, it would help to assess your theory.
This area is covered with mountains. Depending on the end points of your trip you could be gaining say 3000 ft one way.

And even, if ethanol free petrol was so much better - on a 1000-mile range you will save about 6 dollars (that is for a 3 USD/gallon price, if you make it 5 to 5.30, it will be 15 USD saving).

 

I can go from less than 3000 feet asl to over 6000 feet in 8 miles. Gas mileage on the dash varies widely depending on which direction you go, as you might guess.

 

It is a well known and documented fact that ethanol based fuels are less efficient but it does allow them to sell more fuel

 

Yes, it has less energy, but it is within margin of error...
Statements about 10% less energy are wrong.

If you compare energy density of petrol, E10, and ethanol using energy per volume, you will see how close they are.
Petrol is 34 MJ/l
Ethanol is 24 MJ/l
And the mix, E10, is 33 MJ/l

So the difference is barely there.

 

If we are talking 33 vs 34 then it's about 3% difference.