Miles vs MPG (KPM for metric versions)
 

I use the app "pure gas" to find non diluted fuel whenever I head north.

The Last time I did, I was disappointed to not see a bump in mpg like i used to but on the second half of the tank my mpg went from 19 to 22-23.

You won't see that much (15%) bump in mileage from pure gas Andrew, but you can see up to a 3-4% bump. The octane level between pure premium and E10 premium is the same, so the energy content of the gas is the only difference, and that is right around 3%. But that small of a difference is not really noticeable unless you are logging ALL of your tanks (5% change at 20mpg is only +/-1mpg). That is less than the normal variability from top-offs at the gas pump, so it's very difficult to detect that kind of a gain or drop at all.



When pure gas is less than 3% more expensive than E10 premium, I will buy it every time, but it is really hard to find at that price.