Race gas

I have heard before that race gas makes your engine burn cleaner. If this is true. Could you run race gas if you were going in for a smog test and perhaps get better results??

define race gas....

Something like 120 octane

Nope, It won't burn cleaner. Race gas is 110 and usually leaded. I would guess you would fail a smog with that. It is good for a turbo car or even a car with a nitrous kit to prevent detonation. All it will do for you is make your car burn a little hotter. It does smell good though.

all a higher octane gas does, is makes the burn slower so as to reduce knock