Seth, your fuel additive is probably--wait for it--ethanol or methanol. Better check the MSDS online and find out with what you are poisoning your TW.
Per unit of volume, ethanol has only about 5/8 the energy as gasoline. Therefore, it is physically impossible for E10 to provide any more than 93.75% of the power and efficiency of gasoline, and that is assuming that the ethanol burns in the gasoline engine at the same efficiency as gasoline, which it doesn't. Ethanol requires about 4.5 points higher compression ratio, about 10 degrees more ignition advance, and about 37.75% richer fuel mixture than gasoline to burn efficiently. Therefore, if the ethanol burns at half the efficiency of gasoline, you're lucky, and your net is 90.625% the energy output of gasoline. Also, since ethanol and gasoline do not mix, a chemical must be used to make them stay mixed, and the chemical does not burn, so its presence reduces the total amount of fuel in the mixture. There are 36 chemicals approved for improving miscibility, and they compose 8-33% of the final mixture. Some of these chemicals actually provide some energy value to the fuel, but much less than ethanol. Miscibility additives with energy value generally require higher concentrations to be effective. Miscibility additives that do not provide energy vaslue tend to require 12-18% concentrations. Miscibility additives that work with low concentrations actually inhibit combustion of gasoline and ethanol. Result is the best any miscibility additive can do is an additional 4.5% drop in efficiency, most are worse. Some significantly worse. When it's all said and done, it is physically impossible for E10 to provide more than 11 or so % of the power and efficiency of E0, in an engine tuned for gasoline, even if the air:fuel ratio is properly adjusted to compensate for the change in formulation. In practice, the real power and efficiency loss runs 17-23% in most vehicles, and can easily exceed 40%, depending on the particular circumstances.
Them's the facts. Like it or not.