My experience mirrors yours. But before you start calling BS on people reporting Ethanol related loss in MPG, keep a few things in mind.
First there is an amazing variability to any engine and its injection of gasoline. I got a 5.8 1 ton, long bed extended cab Pickup that got better fuel mileage than an identical Bronco with the same 5.8 and trany in it. 1500 lbs difference and the pickup did better. Same engine combo and trany and the guy I knew got worse like 8 mpg out of an F-150 than the Bronco. You could spend a few million figuring it out but the data was all good and consistent. He tried all sorts of add ons, never got it any better. The pickup clearly was the high variable luck of the draw, the Bronco was probably the Norm and his pickup was the low one on the totem pole (worst)
When one guy says he sees no affect and another one says he sees significant (and both take good data) you are seeing variably of how the FI and the Engine combination work individually. One does not care and the other is affected by ethanol. What you can't measure is the variability in the FI system and its engine cohort. You are assuming its identical and my experience and data says its not.
My job was technician/engineer. I know how to take data, I know the variability involved. I don't jump to conclusions
Prior to hitting Washington state with its Ethanol, I was running 37 mpg, tank in, tank out, steady on mountains or not, cooler temps (down there 70 was cool) or hotter (90+) . The variation was 2 mpg. I saw a 36, I saw 38 and the usual was 37. I was quite tickled as that was what was advertised and often that is not true.
First tank in Washington State and it hits 33 mpg. Hmmm, Ok, The TE (technician engineer) kicks in, I was going though a series of mountain passes, maybe more than previous though I had been through two similar, its possible the profile of climb and decent was different.
So, the fuel up is on the flats, no wind, steady driving at 60 mph , and next fuel up is 33 mpg. Same thing again next fill up, a bit lower speeds, country trip, little town traffic, 33 mpg.
So, heading to the ferry no fuel stations on the way, down 2/3, no big deal, I can fill up in Haines. Did so, 38 mpg despite going from sea level to 2500 feet. Then 40 mpg, then 38. What changed, Ethanol was diluted in Haines enough to factor it out.
I ran 37 mpg average until winter hit, then dropped to 33 again (and last was 30 mpb). Ok, what changed, AK shifts to a winter fuel with Ethanol in it.
So, don't tell me I have not taken my data or there were variables in it that changed that, enough runs under virtually identical conditions with significant different results that only change was introduction of Ethanol. . Flat easy cruising I get 37 mpg average, sometimes a bit better, throw in Ethanol ? 33.
Fear No Gravel
Formerly Owned: ( various rides on others)
2 x CB750K (one a true Japan Model flown to Hawaii by a P3 Orion Sub Patrol Aircraft!)
1 x CB700 SC ala Shaft Drive Nighthawk S (RC20 is the actual in house production Model)
1 x R80GS (ok to start with, learned to love it for what it was)
1 x CB450K
1 x 2019 cT Terracotta
What I Did (I quit June 2 , 2019)
Mechanic/Technician/Engineer: Electro Mechanical Systems