The purpose of octane is to slow down the rate the mixture ignites. The higher the octane, the slower the fuel mixture ignites. High compression engines require high octane because the heat and extreme pressure will cause the mixture to ignite prematurely. A high compression engine running low octane fuel will not produce as much power. A normal compression engine running high octane fuel will not run better. It is a waste of money. Only a high compression engine will benefit from high octane fuel. The petroleum companies explain this in the fine print.

High octane pump gas is not the same as race fuel. Race fuel is oxygenated among other things. It will help most engines run better. It costs over $5 per gallon.