This necrobump got me curious. I decided to reset my average MPG counter before starting my commute home yesterday. After a 34 mile drive home, I pulled into the garage with an Average MPG of 32.8. This was after a mix of Traffic, lights (14 of them I believe, stopped at roughly half of them), city driving at 45 MPH and highway driving up to 70 MPH. 2006 2.4 running on Premium with 201XXX on the clock. After putting around our city, running errands and such with the family (and grabbing our free coffees from WAWA ) Average dropped to 26.8. Another commute this morning and Average is at 28.9. I do drive pretty easy, keeping revs below 4,000 at any given time. Just food for thought!

 

Published gas mileage is still based on real gasoline without ethanol. That's pretty hard to find nowadays but it is the standard Ethanol delivers more power but gaa mileage always goes down. Occassionally it happens that you get a tank og gasoline that doesn't contain ethanol by accident. For instance, there was a supply chain shortage of Ethanol during the pandemic. Three major plants shut down and hand sanitizer demand overloaded the market. During that episode, for more than 12 weeks, people experienced an extra 4 mpg in their four cylinders.
California was the last state to adopt Ethanol once it was introduced nationwide. That was mostly a supply chain issue. When the HHRs came out in 2006 I rented them all over the country. They averaged 34 mpg if you drove them far enough on the hwy, but only in California on real gas. Those days have passed.

 

All true. Of course, 10% ethanol should have a trivial effect on fuel economy. Keeping the injectors and combustion chamber clean with “TopTier” fuel will help. Also clean MAF sensor and throttle body matters.

Since we’re talking about E85, that’s 51-83% ethanol. It would be improper to sell a blend lower than 51% as E85 but I don’t doubt that it has happened. Maybe it was even technically legal during the pandemic. I hope not.

I’m quite sure E10 has been improperly sold with more than 10%, too.

As you surely know, economy in blends is not as simple as btu content. Ethanol can burn MUCH more efficiently than gasoline. This offsets some of the btu content difference. How much depends on the engine design, including ECM program. Ethanol also tends to burn much cleaner, to ensure continued efficiency and improve engine life. We’re talking “FlexFuel” or equivalent engines here, of course. It’s inappropriate to use E85 in an engine not designed for it.

 

I have hundreds of thousands of miles on HHRs with more 400-mile highway trips than you can imagine. 10 percent ethanol drops the fuel mileage significantly. Yes, there may be some advantages to ethanol, but fuel mileage isn't one of them. Going up and down hills, wind direction and speed, vehicle speed, number of passengers and luggage, even driving in the rain reduces fuel economy as it takes energy to flatten millions of rain drops and push that little wave of water in front of the tires, mile after mile. Fuel economy is not as simple as measure the miles and divide it by the gallons. Try the same trip without ethanol for a plesant surprize.

It's probably worth noting that when the fuel truck delivers premium gas to the service station and has some left over they take it back and put it in the regular tanks. They never put low grade gas in the premium storage tanks, but itvis okay to mix premium gas in the lower octain tanks. Sometimes you just accidentally get a good tank of gas.

 

You sure about that ? I think the fuel feds would frown on that. Also might be highly illegal and get a hefty fine.
I used to order gas back in the late 70’s and early 80’s. Worked at a full service gas station. You don’t order more than your storage tanks will hold.
And why mix with a lower cost fuel. You would lose money on the resell.

 

Pretty sure!
https://hackaday.com/2021/05/17/gass...ution-network/

The link says that large slugs of different octain gasoline is pumped without dividers/separators and the intermixed product is pumped into the lower quality product because it is okay to sell a little better quality product but not so a lower quality product.

 

With respect and appreciation for your vast driving experience, anecdotes are not science. Unless you kept careful data, we're just dealing with perception.

I would invite a plausible explanation for how just 10% ethanol could cause a consistent noticeable difference. Energy content of E0 varies by considerably more than any reduction due to 10% ethanol content, so a particular sample of E10 could actually have MORE btu/gal than one of E0. The averages are very close, well under 1/2 %. Seems like it ought to be a bit more, but difference of additive, and the solubility of ethanol in gasoline plays into it. The energy content is so close that even the DOE treats then as the same for that purpose, and E10 is the standard fuel. Keep in mind it's MAX 10%, and might legally have as little as 0%, which does happen due to any number of reasons having to do with market price and availability.

E85 is quite different, of course, with only 80% of the btu content, give or take quite a bit. In in the markets where it's com only sold, the price difference normally more than compensates.

 

Yeah. You misread the article. Nothing in there about returning delivery trucks with extra product. The article was about it getting mixed before the tank farms and loading of the trucks.
30 years as a professional Firefighter I have studied a lot of the local tank farms and delivery systems. We did a bunch of fire pre plans there. Spent my entire career near the waterfront where those farms were.

 

True of pipelines but you were talking trucks. The only divider in a pipeline is the clock, trucks have different compartments that dispense by gravity, what is in the compartment dumps into the underground tank.
The alcohol and other additives are added to the gasoline at the truck loading rack, that is why you sometimes see generic trucks deliver to brand stations. There can be errors made at the rack.

Every tank farm has a lab that tests the octane in each pipeline delivery. Jet fuel samples gets sent out for further testing.

 

Okay. I only meant to share perspective. I didn't misread the article I simply stated if they do it in one situation they do it in another. It isn't illegal to mix a higher grade gasoline product with a lower grade product.

There are several easy to find articles stating the following. I found this at mauioil.com

"Ethanol contains roughly one third less energy than ethanol-free (also known as non-ethanol) gasoline does, which means you will get slightly fewer miles per gallon if you use E10 or E15. The fewer miles per gallon you get is small, but measurable. Vehicles will typically get 3-4% fewer miles per gallon out of their vehicle when running E10. For E15, the amount goes up to 4-5% fewer miles per gallon. For example, if you’re driving a vehicle that gets 32 miles per gallon, and you’re running E10, you would get between 0.96 to 1.28 miles less per gallon, taking you down to between 30.72 to 31.04 miles per gallon." It is a noticeable difference if you pay attention to it.