Performance by Octane Rating of Gasoline Used

Gas Mileage

Here's some interesting trivia about gas mileage. Have you ever wondered which brand, grade, or octane rating gives better gas mileage? Well, I've collected thousands of miles of data on a wide variety of brands, octane ratings, grades, etc. All this information is from my 1976 Toyota Celica. I have found these results interesting, I hope you do as well.

Octane Rating

I always though that a higher octane rating would give better gas mileage, so one of the things I started tracking was the octane rating of the gas I was putting in the tank. One thing I noticed pretty quickly is that the a given grade of gasoline can vary from one octane rating to a different octane rating depending on where you are getting it. I have noticed variations between octane ratings from one brand to another in the same area as well as variations in octane ratings within a specific brand from region to region.

So, I thought this report on the results I have seen from different octane ratings could be interesting, if not useful.

Octane entries only listed if I have more than ten records for a specific octane to try to minimize the impact of deviant results.

RatingNumber of EntriesAverage MPG
85 176 17.81
85.5 533 20.96
87 236 20.97
88 174 19.18
89 37 24.06
91 227 18.32
92 18 23.09

I, of course, make no guarantees about what kind of gas mileage you may receive in your vehicle, even if it is a '76 Celica with a 20R and nearly half a million miles under the hood, because there are way too many variables that come into play...