I just made my annual vacation trip towing my roughly 6k aluminum jet boat full of 50 gallons of fuel and food, drinks, clothes and toys and would guess my actual payload including the boat was roughly 7k plus the fully gassed truck. The trip involve going from Sacto Ca to Lake Almanor via highway 70. Sacto is at sea level and the peak elevation was roughly 4800 feet. It was 390 mile round trip and were somewhat lighter on the way home. There are also some 6% grades on the trip but they are at about 2000 foot elevation. Speed on trip was about 60-62 on the flats which is roughly 80 miles of each leg. In the hills and in the canyon it is somewhat windy road but speeds vary from 40 to 60 MPH. My average fuel economy during the complete round trip was 12.6 according to meter in dash and i would guess calculated would be roughly 12.4 or so as that is usually the difference when i hand calculate. My truck is a 2018 Lariat SC FX4 with 3.5, 3.55 rear and only 2500 miles or so on truck. I left unit in tow/haul mode entire trip including the flats. My air conditioning was on the whole time and the air temps were in the low to mid nineties both directions. I also only use 87 octane fuel same as i did in 13 which was same truck with 6 speed trans only difference. I also dont baby the truck as i was pulling the 6% percent grades as curves in the road would allow 50-60MPH.

MPG’s during majority of my 140 hwy miles this morning were between 19.5-22 @ 75-80mph @ 1600-1800 RPMs, 9th or 10th gear. It’s crazy to me that the trailer ramp is keeping me down that bad.