That’s awesome if it holds. I tried and at least on an 1500 mile highway trip I saw zero difference in mileage either way (750 out with 91+, 750 back on 87). 12 mpg both ways. Going 80 doesn’t help I’m sureI've switched to 91 octane for the last few tank's and am consistently seeing higher KCLVs now on my very repeatable drives to and from work. I had been consistently between 10 and 12 and now on 91 octane am consistently between 13 and 15 for what it's worth. Also see about .5 to 1 mpg better mileage. Not 10% better to match the 10% higher cost but I think I'll stick with it.