toluene is added to gasolines (especially race fuel) from the refinery, It was first phased out by MMT which does the same thing but is a waste product of plastic production so it's dirt cheap for the refineries as they would just dispose of it otherwise. Then the EPA being the way it is and MMT making ground water under a spill zone taste like crap, ethanol has been getting phased in as the new octane enhancer/oxigenator, even though it costs significantly more. Government subsidies have been put in place to make the ethanol affordable for the gas companies. My guess is most people don't know about toluene (also called toluol at the sherwin williams) or that it can be purchased locally for next to nothing. I went into the sherwin williams asked for toluene and he said "we only carry un-recycled automotive grade so it will cost more" $35 dollars later i walked out with 5 gallons which is enough to treat 95 gallons of 93 octane fuel and achieve 110 octane. I wish i could get my hands on some propylene oxide but the EPA began regulating it as it is known to the state of california to cause cancer
what isn't? also if you spill propylene oxide on yourself you better get rinsing as it is a skin absorbed poison.