Also in Can and I run 91 almost exclusively (wife sometimes puts in 87) and avg 12L/100kms (19.6mpg) (manually calculated) during the summer (winter ends up being 15L/100kms). The summer after I got the truck (had around 40k kms on it) I ran 3 tanks of 87 to ensure I didn't have any residual 91 in there and I avg 15L/100kms (16.8mpg). I drove the same route with the same weather over the span of my testing. I also noticed a change (for the worse) in how the engine idled, accelerated, and at cruise when on 87. I friend of mine has the Sport model, I have Outdoorsman, and he's seen similar results. We both run 91 exclusively and when we can get it at Costco for same price as 87, and I've talked to the truckers and where I live, 91 is straight gas, no ethanol in it.