From what I have been reading the hydroxy works as a combustion aid allowing a more complete burn of the gasoline therefore equaling a higher volumetric efficiency. As a result you can lean out your air to fuel mixture = less fuel used = higher mpg. Similar to running propane injection on a diesel motor. The cells in this discussion draw 10-20 amps to run so even if you upgrade your alternator to a maxima or quest one you will still gain mpg because your hp to run the higher amperage alternator won't negate the decrease in fuel usage. Lets say you gain 5mpg from adding the hydroxy but lose 1mpg from having to drive your alternator harder, you still net 4mpg.
JP