What matters to me is the total cost of operating the truck over time. Most of the time (~99%) the camper is on the truck, so I may see MPG’s as high as 12.5 (downhill, tailwind, ideal driving conditions, etc) and as low as 6 (chugging up a steep grade, during regen, speeds above 65, etc).
I used to keep track of fuel mileage in my older trucks with handwritten logs. Even after vehicle’s started displaying MPG on the dash, they didn’t seem to be that accurate all the time. On both my 2010 and 2016 F450’s though, I hand calculated the fuel mileage for the first few months I had them and eventually concluded that what the truck was displaying was pretty accurate, so I quit doing it manually.
This display showing the average MPG I’ve never reset. I’m not sure how many miles it’s averaging, but it has to be several hundred at least. Or maybe it’s every mile I’ve put on the truck. All I know is I have to drive several hours at an MPG higher/lower than it’s displaying before it will tick up/down .1 of an mpg. As far as I’m concerned, that’s what my average MPG is for this truck. Keep in mind that most F450 pickups have a 4.30 axle ratio. I think they could be ordered with a 4.80 as well, but those are pretty rare.
I use the trip odometers to get a more focused idea of what my MPG is. The “A” trip odo is where I keep track of how long it’s been since the last regen. When the regen starts, I’ll reset it and keep an eye on the mpg. It will be significantly lower than normal during the regen process, and will start going up noticeably when the regen stops. Between this, and the DPF soot load screen, I can keep pretty close track of what’s happening. The “B” trip odo is the one I reset a lot.
:):)