According to this report (see attachment) a clogged air filter does not reduce fuel economy at all....

or if the attachment doesn't work visit this website...
http://www.fueleconomy.gov/feg/pdfs/...02_26_2009.pdf

 

yes ,,so does putting your tires to 40psi, so does a new wax job, also not going over 55 MPH. jim

 

That is nonsense. Clog up your filter and see what happens. If nothing else, you will loose HP and mileage just because of the work the engine has to do to suck air to run.

 

Restrictions to an engine breathing and turning causes the engine to use its power to turn against itself instead of just the transmission and driveline. Allowing the engine to breathe (in and/or out) easier or reducing friction inside the engine (roller bearings) requires less energy from the engine to create the power that is needed to turn the wheels. Take off a pulley from the belts and there is about 10-15 extra HP (=increased efficiency) becuase of less resistance. Add roller rocker arms, roller cam shaft, roller timing chain (older engines) and you have increased efficiency. take off exhuast or intake restriciton or in the srt6 case, actively push it in with a supercharger.

An example is the new ford power strokes have two turbos to push the air through the increase regulations of more exhuast cleaning (increased restriction). Take away the restriction in the exhuast, and wala, you have increased fuel economy (also more power and throttle response). The two turbos were required to maintain the same power due to the new exhuast restrictions. It uses more fuel to push past the increased restriction......

 

Under steady-state cruising the computer in your car is controlling the throttle body (among other things) to regulate the amount of air ingested by the engine. Remember, the throttle is an intentional intake restriction. A decrease of restriction in the intake tract elsewhere will be matched by a slight closing of the throttle body to maintain the level of airflow the engine needs for the same steady-state cruise. The pumping restriction seen by the pistons will be the same. They don't know whether it is a clogged filter, or the throttle body causing the restriction. Your fuel economy will be the same. Full-throttle acceleration will be improved with a clean air filter.