Can I use 100+ octane racing gas in my car? Is it worth it?

DSMs will realize some performance benefits from ultra-high octane gasoline.  The extra octane will allow the ECU to advance the engine timing more.  Some people report significant gains with race gas, while others describe only minor improvement.  The prohibitive cost of these fuels generally restrict their use to drag racing applications only.

Note that this applies only to true racing gasoline, and not pump gas plus octane boosters. For more information, read the very detailed Gasoline FAQ (alternate link here), and this essay on high-performance gasolines.

For those who can't afford "straight" race gas, try using the gasoline blending chart provided by Osborn's Auto. Be certain to read thearticle that accompanies it.