Just put half a tank of 94 in this afternoon and it's like I got a Pedalbox installed or something, very noticeable response and performance difference.
Our fuel has up to 10% ethanol in 87 - 91 grades and I swear it may as well be up to 10% corn syrup.
If your 94 is E0 or 100% real gas you would be better MPG as real gas has more energy than E10 or E15 or E85 and you should have more pep.
I saw that this summer as we took a trip from Texas to Minnesota and back and tried to fill up on as much E0 as we could. We were also taking the back roads and only doing 65mph on the roads so we were getting around 23 to 24mpg and the truck seemed to be doing better overall and i did notice that when the truck was at idle that it was smoother.
Right now I tanked up the truck with 20 gallons of 93 last night and I have noticed that the idle is smoother than when running 87 so I am starting my experiment to see.
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2021 Land Cruiser Blizzard Pearl
I may just start filling with half a tank or 87 or 91 (with ~10% ethawaste) and half a tank of 94 to "water-down" the ethanol content. Pushing a $1.80/l for 94 isn't that cost effective but in my opinion ~$10 a tank for a happier machine is worth it.