Used to drive the speed limit. If that was 70 then it was 70. I saw some 80s out west and decided not to go that fast. So at 70 I was being passed but it was much easier driving. Then I tried going 62. It is where I shift into 6th gear. Now I run 61-62 and get 8 mpg instead of 7.5. That makes a huge difference. I noticed it first putting on the resonator. I saved 178 gallons going from VA to WA and back. So this trip it will be slower. I built in an extra two travel days but I bet I can save 200 gallons of fuel over the trip there and back with the resonator and a light foot.