Toluene can work also, it raises up the ole Octane too. Cleans internal engine parts, fuel injectors and such. I would put about 1 gallon per 10 gallons of fuel. Though raising octane if your engine isn't pinging and knocking is worthless, it does have some decent cleaning agents. After you run the tank, fill with your normal fuel and heat engine and head to emission test.

Most the time if your going for a smog test, get the motor to full operating temp. Not a short drive either, you want to hit the freeway and really get things warm. Then get to your smog check as soon as possible.