Well, a K&N air filter isn't going to work miracles, but it DOES help both fuel economy and horsepower. You're right, the amount of FUEL that goes into the engine IS controlled by the computer, but airflow is controlled by the throttle body and air intake path. Most of an engine's fuel is spent fighting the resistance of incoming air. The engine vacuum is contsnatly placing a load on the cylinders that are firing, so all that force = wasted fuel. when you have an air cleaner that allows for more airflow, that's one less thing that the engineis fighting. Plus more air allows a cooler, denser intake charge, which improves power, and economy. You also don't have to open the accelerator as far to get the same emount of air with a K&N air filter, which means the computer isn't automatically dumping more fuel down the intake just because you pushed the accelerator pedal. I dunno, it's not an earth shattering difference, but it is well worth the $30 they charge for it. If nothing else, just because you don't have to buy a new air cleaner every time it gets dirty. you just take it out and cleanit in warm soapy water. Dry it out, and spray oil on it.