[serge944]

I think a lot of your are overlooking a huge factor.

When your air filter is clogged to the point of causing additional restriction throughout the rpm range, you are operating at lower volumetric efficiency. Meaning, you are making less power at each point throughout the rpm range.

Now, given you have a certain driving style, you will have to go higher in the rpm range to extract the acceleration that you like to passively utilize.

If you have to operate at higher RPM to produce a certain amount of power that will propel you with a certain amount of acceleration, you will be using more fuel per marginal amount of power.

There is a reason 6-7 liter american cars can get great gas mileage. They produce so much power at low RPM that revving the engine isn't necessary. Back to the whole volumetric efficiency thing...