The ethanol free I'm using is 90. And on road trips I've been using octane boost and see good increases in MPG, cause I'm usually trying to minimize stopping to every 3-3.5 hours.Not much really. The ethanol free gas tends to be on lower octane. I'm experimenting now with regular gas to see what % drop I see in mpg. I do notice a slight performance decrease but in the end the numbers will tell.