Hmmm, I have been clocking 18-19 around town (even with 4.10) but that is when I am just driving it lightly. In those cases, I pretty much just use 2nd, 3rd, 5th. My best on "mostly" highway was 25.2 MPG. I am running rich according to my A/F on the dyno so I expect my mileage to go up a bit once it is tuned.