Great question! Assuming you’re using the product at the recommended concentration of 1 oz/gal of gasoline, your observations are contrary to those of most users. Typically, the cleaning agents can positively impact the fuel system quickly enough that a positive difference in power and performance can be felt. That said, in a relatively clean fuel system, one that is routinely maintained by B-12 Chemtool, for instance, your observation can actually be explained by the presence of the solvents themselves. It turns out that the oxygenated solvents in the cleaner are great at removing gum and varnish do not offer as much power as the hydrocarbons in gasoline. That’s why E85 fuel burns cleaner but gets lower fuel economy than E10 gasoline. The difference in the fuel economy of a clean system should be minimal, but that difference (along with cleaning efficacy) will increase as the concentration of B-12 Chemtool is increased.