High-octane fuels will not burn poorly. It just isn't necessary to increase octane further once the threshold of knocking/self-ignition at the target compressio

High-octane fuels will not burn poorly. It just isn't necessary to increase octane further once the threshold of knocking/self-ignition at the target compression and cylinder temperature is reached. Plus you missed the point: In many places the premium fuel is the same octane number as regular (e.g. 95), but premium is with additives for <insert vague marketing>.