At least in the old Corvette hobby, this is closely followed by the leaded gas myth. Despite the lack of even one example of an engine being damaged by lack of lead in over 40 years time frame, there are those who still insist on seeking out miracle additives. I doubt we'll see the end of either myth in our lifetime.

Speaking of ethanol and Corvettes, there was a commercial rebuilder of the Rochester FI units who for years insisted that E10 would destroy the units. When asked for proof, he would display photographs of obviously corroded components. It came to light later that these components had been removed from a sunken speedboat and that it was salt water that caused the damage, not ethanol. It also came out that his reason for labelling ethanol as Satan Incarnate was that he was quietly trying to dump an inventory of inferior non-compliant pump components on unsuspecting customers that quickly failed when exposed to E10 .

 

So I have a friend who switched to ethanol free gas and in their SUV went from about 14 MPG to 17 MPG. They said they tracked the MPG on several tanks before and after the switch to get a more scientific result. I just can't fathom how the increase would be that much... either way this person now is preaching ethanol free gasoline like it cures cancer.

I feel like maybe some subconscious soft pedaling after the switch may be giving some confirmation bias, or maybe ethanol affects different engines differently.

 

That's over a 20% increase in mileage!

E10 is 90% gasoline and 10% ethanol. Even if ethanol had zero energy content and was just 'taking up space' that would only account for a 10% difference in mileage between the fuels.

As Doug has pointed out E10 is nothing new. It's been around for decades. If there really was an easy to see and marked difference in fuel mileage, where's the public outcry and front page scandals?

Your friend has quite an imagination.

The reality is that E10 will cause a 3% difference in consumption as ethanol has 90% of the energy of gasoline. If your friend was getting 17 mpg with pure gas, he'd get 16.5 with E10. Most people can't measure stuff that accurately as they already get a much bigger variation from tank to tank from other factors- 'soft pedaling' as a perfect example.

 

Not confusing in reality as the main default products are all ethanol free (at least at this end of country) . You have to deliberately seek out fuel with an ethanol content and the pumps are labelled e10 or e85 (E85 is not at all stations). Never noticed if they also state an octane level as I dont buy it.

E10 is the cheapest gasoline type fuel here, which compensates for the slightly higher consumption.