Change Fuel Grade to Improve Power/Mileage???

I'm running a new Tundra w/5.7 and 4.11's. No problem with power but looking to tow in some mountains and wanted to know if anyone has "bumped" fuel grade to get some extra power/MPG from their tow rigs.

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I usually used 10% ethanol blend gas in my truck but switch to no ethanol when towing. A bit more power and much better fuel economy.

I don't know about the Tundra, but I used to have a 2010 F150. 4.6 3V gasser. In New Mexico, where the regular is 86 octane, I bumped up the grade and noticed that my gas mileage improved by about 2 MPG so after that I began to use the higher grade when I towed. I had an Edge, so power really wasn't an issue becaise it was so light. I switched to diesel when I got the North Trail and the MPG is much better than it was with the gasser.

When traveling in Iowa, I would put in the middle grade fuel because it cost less but it also had the highest alcohol content. Seemed my mileage went down with it. When I go back to Seattle, I asked my mechanic about it and he said he had run into many vehicles that did not do well that gas. Recommended using top tier gas so I have mostly done that since and mileage has improved again. My Suburban is 9 years old with 70,000 miles on it and is in terrific shape. My old suburban (an '88) would run on anything just fine except when pulling a trailer. Put a better grade, not higher octane, and it pulled a lot better.