[zeebee]

If your vehicle calls for “regular”, know that it will get 10-15% better mileage on “premium”.

Entirely false and backward.

The more octane, the more additives equals lower percentage of fossil fuel.

You will get better mileage on less octane as long as your engine won't ping from valve clatter.

[Mariner]

In my Tahoe I have tested the premise, and verified it.

My mileage range goes from 16 even (87), to 17.8 on 91 octane.

Freeway mileage on long trips.

At least 800 miles.

You can argue what should be and what the science says until you are blue in the face.

I have real test results, verified at least 10 times with precise measure.