【註三】The actual “recipes” for these octane boosters are closely-kept trade secrets, but most of them use one or more or the following ingredients to raise the octane of regular pump gas: methylcyclopentadienyl manganese tricarbonyl (MMT), toluene, and variants of trimethylbenzene. MMT is a common ingredient in lead substitutes as well as unleaded gasoline, while the others are hydrocarbons derived from gasoline production itself. Ethanol is also a popular ingredient in octane boosters, because on its own, ethanol already has a very high octane rating (roughly 110)。https://www.knowyourparts.com/technical-resources/fuel-system/fuel-additives-octane-ratings-explained/