I’ve actually been testing this for a couple of years in all three vehicles. easily going through 10+ full tanks of E0 and 10+ full tanks of E10 in each vehicle. So, I think my sample size is enough, right? 
I don’t doubt your findings, but you do realize you are probably the only person on any car blog that is reporting better fuel economy using E10 vs. using E0. Please read some of my recent posts when you get a chance, because after reading yours I’m even more confused about the whole Ethanol thing. I’ve been conducting my own fairly accurate tests on three vehicles I own and have found that I’m getting 10% better mpg using E0 vs. E10. Very strange!
You should get better mileage from E0. Are you questioning the level of increase? I originally thought you were questioning the variation in results between vehicles…
Sorry for the confusion, but I’m questioning the 10-12% difference in using E0 vs. E10 in all my vehicles. Not the difference in the three vehicles. I’m simply amazed at my findings - 10-12% better mpg using E0. I really believe my data is good too. So, how can the EPA and other government and even non-government organizations say it’s only a 3-4% loss using E10? It’s laughable! I can see the testing now. They (The government) probably drive 50-55 on a flat highway using the E10 and then drive 65-70 using the E0. My findings using three very different vehicles from 2001 up to 2018 are all showing a 10+%. It’s crazy!
The 3% estimate is based on the difference in BTU/gallon of the two fuels.
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No they don’t . Have you even considered the percentage of the price difference ?
Now your on to something! So, they (the government and others) are literally just testing the actual fuel in some lab VS. actually using 20+ different cars from different years to get an “Real World” number. What a joke! So, when is Ethanol going to be outlawed! Everyone knows it’s an extremely low energy and inefficient fuel. What a government scam!
Ethanol will be around for a while. It started primarily to reduce foreign oil dependence, but now has political overtones-keep the corn farmers happy. A number of years ago, in the same issue, our newspaper published two studies. One showed a net loss (more oil required )one showed a minuscule net gain (less oil require). These studies looked at the costs to produce the ethanol along with the reduction of miles per gallon.
As far as cost difference, runs $0.50-$1.00/gallon more where I live.
Note, modern marine engines are designed to run on E10, but, because the boats often sit for long periods in damp conditions the E10 absorbs water then the water separates out. Most boat owners op for non-ethanol gas.
E-85 - yes…But not E-10. E10 is used as an oxygenate for emissions.
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Yes, the break even is about 20 cents/gallon and I know I’ve wasted money doing my tests. I also don’t believe they (the government) actually does “real world” tests to come up with their 3% loss. Texases is correct! They probably literally just test the actual fuel in a lab and don’t use any normal everyday vehicles that people actually drive. For a fact, I’m getting 10-12% better fuel economy using E0 in ALL three of my vehicles. I’ve driven 435 miles (got 22.9 mpg) in my Volvo XC90 V8 using a full tank of E0 (all interstate). The same exact trip using E10 fuel I could only get 360 miles (got 19.1 mpg). Both trips used 19 gallons of fuel ± .25 gallons. That is a ridiculous difference, but it’s probably because the Volvo has a Yamaha marine engine in it that was modified to work in the Volvo. It’s a great engine that quiet and very powerful. It obviously gets horrible fuel economy using either fuel, but the E0 difference is huge!
Correct, but my Volvo has a 2009 built Yamaha engine in it. The mpg difference in my Volvo is huge during long interstate drives. Since everything else is equal it has to be the E10 fuel OR perhaps other additives that are added to make the E10 fuel work in our engines. I simply get horrible fuel economy using E10 fuel and I have no idea why it’s such a big difference.
one of the things you mentioned that E0 you are using was not always 87 octane, it may be an important clue
I have 2006 Nissan Pathfinder and it is perfectly fine on 87 (it is in specification), but has a note “for the best performance use 91” in both manual and on gas door
if I run it on 91, I will consistently get 3-5% better MPG and better power, it is also not only my observation, but multiple owners report the same on Nissan-specific forums
You miss the point of federal gas mileage testing. They do it so that car buyers can compare fuel mileage from different cars all tested the same way. It’s a lab test designed by EPA and DoE and executed by the auto manufacturers. They even tell you that your mileage might be different. Here’s how they measure it. They also only E10 and E85 if it is a flex fuel vehicle.
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I wonder what’s the typical moisture content of E10 gas by the time it reaches the pump nozzle, since ethanol is hygroscopic.
Not enough water for the ethanol to drop out of solution, but maybe enough to reduce engine efficiency?
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That means the engine is designed to run on 91 octane, but running 87 octane is fine because the knock sensor will kick in and retard the timing for less performance and lower mpg. If an engine is designed to run on 87 octane then using 91 octane will have ZERO effect on performance and mpg.
Nissan clearly states 87 as required gas, most owners use 87 and this engine goes hundreds of thousand of miles on 87.
We can debate if it retards timing for 87 or advances it for 91, but does it really matter? 
Let’s settle that it ADAPTS timing.
I can give another example of the same: Mazda’s 2.5 liter turbo engine - it’s multi-grade per spec and is perfectly fine on 87, yet on 91 it gives some extra power output (on high RPMs only) and lesser consumption (unless you get too inspired with zoom-zoom).
I do agree that some mid-70s engine with fixed timing might have zero effect from converting to 91 as it has smaller compression ratio and is simply not capable of benefiting from the higher octane fuel…
Hey… wait… from what I recall, 91 even has slightly less energy packed per the same volume, so unless engine has sufficiently high compression ratio, 91 may even lower MPG.
Yet once we transition into the realm of modern engines, the reality is that 91 indeed might reduce the consumption in some of your samples.
considering at the 10% level it works as an oxygenate…it won’t be. It’s not a scam. I don’t want to see them increase to E15 or E20, but I’m fine with E10 and my vehicles are too
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Higher Octane does NOT mean more power. All it means is higher octane gives premium gas greater resistance to early fuel ignition, which can result in potential damage.
Actually yes. If you have an engine designed to run on 87 Octane then using 91 octane will NOT advance ignition timing.
But then you added this. Which I’ve seen before on my 98 Pathfinder. It means the engine is designed to run on 91 octane. It has a knock sensor to retard timing so engine won’t be harmed if you do use 87 octane.
Hey, just for kicks you should try using ethanol free fuel in your V70 on your next long interstate trip. I only tried this switch because of a friend and I was simply amazed at the difference in range! I will guarantee you will get 10% or better fuel economy on a long flat interstate trip in your V70. My friend that advised me to try this drives an XC70 and he saw a huge difference too. I realize there may be no cost benefit, but I hate stopping for fuel on long trips . Some stations in my area offer E0 for only 15 to 20 cents more, making it worth the change. Finally, what everyone seems to be forgetting is that over the long haul (100,000+ miles) Ethanol, even just 10%, isn’t exactly good for your fuel system and other parts within your engine. This is especially true during the winter with sub freezing temps. In my area, E10 is never switched out in 90% of gas stations and that’s obviously not good for most vehicles. Well, at least the 95+% of vehicles that are not designed to run on E85. I’m assuming those vehicles are specifically designed to run on even pure Ethanol all year long.
The only thing in my fuel system item that I’ve had to replace in my 09 Focus (over 200,000 miles) is the fuel pump, and I attribute that more to my wife running the tank empty a few times than the Ethanol (plus the bottom of the tank was spotless…). And I live in Pennsylvania, I see sub freezing temps.
They likely switch over to a winter formulation:
https://newsroom.aaa.com/2013/06/what-is-the-difference-between-summer-and-winter-blend-gasoline/
With PA’s state taxes on gasoline, it is usually around $0.80-$1.50 more for pure gasoline, definitely not enough savings with the mpg gained.
That’s an interesting question…I don’t know if flex fuel vehicles could handle E100. As far as I know only Brazil sells E100 as they have vehicles designed to run E100.