My truck is at around 1400 miles now, and the mileage seems to be improving the more i drive it. I've been averaging around 14 mpg with local short trip driving.

I had to travel to Chicago for work yesterday, which was the first all highway trip with my truck. It was a 150 mile round trip on I94 in NW Indiana, and the Dan Ryan and Kennedy through Chicago. Rough traffic on the inbound trip, pretty smooth on the way home. I calculated the mileage at 17.2, the display showed 17.7. That's a bit better than I expected, especially considering the traffic.

My old 6.7 Cummins my have gotten a bit better mileage, but there are a bunch of other reasons a diesel isn't the right truck for me.