It has to be. 100 unleaded is sold at the pump in many Union 76 gas stations in CA, including several in Orange County (I'm not aware of any in San Diego, though). From their website:Steve Grosekemper wrote: If 100 Unleaded is pumped with the price uncluding federal state and local tax, it may be legal.
Our 76 Competition 100 Unleaded Racing Gasoline is the highest street legal octane available. It's specifically formulated for specialty vehicles and will never over octane engines.
All of our Leaded Racing Gasolines are designed for racing applications and are not legal for street use.
http://www.76.com/products/76racing.asp