Having owned 5 different TCs and 4 different Cummins equipped trucks the last 10 years, I get about ...............
I am like Forrest Gump when he was running across the US and said - "When I got tired, I slept. When I got hungry, I ate. When I had to go, you know, I went."
When my truck needs fuel, I fill it up.
MPG is one less thing on my list to be concerned with. Like many of you, I have computed MPGs a time or two (or more). Just don't care anymore.
If I couldn't afford fuel, I would stay home. As far as MPG in Ford, vs. GM vs. Dodge RAM, I don't care.
My fuel tanks holds 35 gallons and I fill it up when it gets to 1/4. My motor home holds 90 gallons and I fill it up when it gets to 1/2. My motor home and my RAM 3500 both have Cummins diesel engines. Go figure!