I just got my 2500 Big Horn 6.4 Hemi and took it on a little 600 mile round trip to break it in before I tow. Half of that trip is over some hills and mountain passes and the rest was on the flat plains. I hand calculated about 13 mpg averaging about 75 mph. Not too bad I guess with the 4.10 and maybe that will bump up 1 or 2 over time and with a tonneau cover. For a big truck, I thought it rode pretty smooth too. Most of the trip, the temperature outside was in the 90's and the AC worked great. A couple things I noticed was the truck seems really loud at startup (like it idles a little higher and seemed to make a little chirping sound), but then I didn't notice it all of the time so maybe it was just when I would first start it up. I also heard a loud clank a couple of times right when it started up. Then at times it also felt a little weird, especially starting out at lower speeds, Almost like a slight vibration or something in the pedal. I don't know, I just never drove one of these before so might take some getting used to on what is normal and what is not. I'll have to pay more attention to pinpoint stuff down, but just wanted to post that I had a good ride overall for the first trip and no problems! Love the truck!