We went for a major 3 week vacation pulling the travel trailer, about 9,000#, loaded with everything. This was the first major road trip for my CTD and here's how it stacked up:

4,915 miles
425.3 gals.
11.5 mpg average
16.6 mpg highest (unloaded sight seeing)
9.3 worst ( had to have been a 30 mph head wind!)

Is that good, average, totally horrible?

The trip was awesome, never a hickup with the truck and she pulls wonderfully, I LOVE THIS TRUCK

 

I just did a 400 mile trip this past week and took on the exact same milage as yours. Well almost, I haven't seen 16.6 unless I hit the reset button going down hill.

Isn't this truck cool, 55 up hills and 1800 RPM. This truck just loves to pull!!!!!