"If the K&N style filter was so good, don't you think the vehicle manufacturers would be using them right off the assembly line? It would be a cheap way for the vehicle manufacturers to increase mileage for almost nothing.. They DON'T because there IS NO GAINS to be had.."
Can't do that as the majority of vehicle owners never raise the hood, and would not have a clue on how to replace the air cleaner, or even think about the proper procedures for cleaning.