Is it true that as my car ages it gets less and less fuel economy?

This is a harder question to accurately answer because it depends on how you maintain your car.  If you continually do the proper maintenance on your vehicle you will generally experience the same level of fuel economy as when you purchased the car new.  Any automobile without regular tune-ups will experience a drop in mpg.  The reason behind this is that the engine will have to work harder in order to achieve the same results as one that is properly maintained.  So by taking care of your vehicle you will not only earn that money back in fuel economy, but you may also prevent from being broken down on the side of the road!

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.”