Comment by PeterStuer

It's more like cars. Different engines have different efficiencies. So filling up a few gallons at the pump will get you less pollution per mile on car A than in car B.

But regardless of the efficiency, if you overfill the tank and the fuel starts to spill on the pavement, that is not going into the milage but straight into the pollution bracket.

The idea that intake is irrelevant is just as ridiculous as the idea that everyone's metabolism is an exact clone.