Benefits of 100-octane gas include increased horsepower, less exhaust emission, better gas mileage, better acceleration and a smoother running engine. Some of these benefits are the result of oxygen added to the fuel mixture.
The increase in horsepower and improved acceleration are, in part, due to the oxygen. Oxygen adds to the horsepower and helps the spark timing that slows acceleration with lower octane gasoline. Spark timing also plays a hand in reduced gasoline usage efficiency. When the spark timing improves, so does the gas mileage in most cars. The car's engine runs smoother with 100-octane gasoline because of the hydrocarbons that vaporize and combust chemicals to energy more efficiently.