On the recommendation of a mechanic friend I dropped one of these into my 1999 Silverado 1500. (202,000 miles and still running strong.) My unscientific testing revealed a pickup of 1 MPG. Not too shabby. When the time comes for a new air filter for my wife's Tahoe, I'll buy a K&N. Plus I can claim that I'm helping to save the Earth because I'm no longer dropping used filters in the trash. You can't put a price on that kind of smug self-satisfaction.