I just replaced my 2001 7.3 powerstroke with a new 2016 6.7 powerstroke 4X4 I know the 6.7 won't get the mileage that my old truck got but once it's broke in what kind of mileage are you 6.7 owners ...
mileage is important on a new truck for a while for me but then it is what it is and the roads etc make a big difference. Until 2009 our dic was perfect for fuel used and mileage. Perfect means the math agreed. Good enough now but a speedometer repair changed the numbers a little. I do heard of some big numbers from guys .