High octane race fuels burn more completely and leave no carbon behind, which leads to greater power and efficiency. Race fuel can also contain proprietary additives that clean fuel injectors, prevent fuel-line freezing and maintain a low build-up of carbon in the cylinders.
High octane 110 fuel works well with race cars, but its benefits are greatly diminished when the fuel is put into street cars. Normal gas pumps provide streetcars with lower octane fuels such as 91. The octane ratings distinguish the fuel's resistance to detonation within an engine, with a higher octane number indicating a greater resistance to detonation. High-power racing engines are tuned to burn fuels with high resistance, but high octane fuel in a low octane engine can result in an incomplete burn, which means a decrease in power output.
Tests indicate that it's not financially economic to fill a tank with high octane race fuels if it already runs well at 91 octane. The power gains are minimal, and continue to decrease with higher and higher octane levels. Race cars don't get higher power directly from using higher octane gas, rather the gas allows the power by keeping their engines, which have typically much more compression and timing than normal vehicles, under control.