I mostly drive streets and before the k&n i was getting about 260 miles on 16 gallons, 300 miles when I traveled more on the freeway. I Installed K&N filter and removed the silencer box a few weeks ago. I'm now getting 270 on the street. I just took a trip yesterday to Tijuana Mexico, cruise control between 85-90mph both ways, I have 301 miles on the trip odometer and a 1/4 tank left. "68 miles to E". Only other factor to affect this increase is I switched my 19's for my stock 17's for the trip. If your wondering, yes I got a speeding ticket, 84 in a 65 NOT EVEN 5 Miles across the US border!