Assuming labnut is talking about the new HO/6speed it would probably be too new to discuss mileage. However with over 1000 views surely somebody has one that's been put to work. From word of mouth Dodge Cummins seems be best in the MPGs for the past few years. Of course that sure ain't scientific as there are those saying they get 12 - 14 MPG with the same vehicle with which I get 7 - 10 MPG. Sure would like to hear some first reports though....
John and Dottie/'06Teton Experience Sunrise/'03Dodge QC LWB CTD 6-Spd 4:10 DRW
I have a 03' Dually Quad Cab 4x4 turbo Cummins HO and just got back from a trip 1k miles each way. I was able to maintain 20 mpg at about 80 mph. I have equipped the truck with an Edge EZ chip and this is how I was able to get these numbers. Now I just need gauges.