Do aftermarket parts such as air-filters help improve my car’s miles per gallon?

Surprisingly this is no longer the case, unless you are driving a much older car.  It was something that was once true for but since the invention and mass use of the fuel-injection engine, it is just another myth.  Often after market companies will use this as a gimmick to get consumers to pay additional amounts for car parts that are really unnecessary.  There has been extensive research done by a variety of companies and none of them found that making these changes improved the automobiles mpg.  Unless you have a heavy pulling truck that you use to transport things, it is really of minimal advantage to you to have make these “improvements.”