Alright I had my first experience in a 2014 Dodge 3500 mega cab, 6.4L, 4.10 gears. We were loaded with four people, a sled deck, and two place enclosed Triton clam shell. Cruising the interstate at 81 mph from MN to CO we got 4mpg. This truck is not for me.
What did the feel good meter say for mpg? The owners of Truck Camper Magazine bought a new RAM 6.4L and carry a truck camper everywhere, the feel good meter was about 3mpg high on average.
I find my 2012 GMC 6.0L gasser feel good meter is within 1 to 3 tenths of a gallon used, incredibly accurate. Not saying my mileage is great, 8.5-15.5mpg depending on the load, but the dang meter is spot on!