just finished a 2588 mile trip pulling about 12000 lbs. (5th wheel)DW kept track and here is the low 9.4 and high 11.9-2013 Dodge 3500 4x4 with 6 speed stick-truck did a very good job-I was impressed!...
Driver behavior can affect mpg as much as 25 to 30%, so my mpg and your mpg in the same truck are not comparable. I've driven with some people who have one pedal or the other to the floor anytime they touch it. Then they complain their truck sucks fuel :S
The only comparison that matters is over the same route in the same conditions with the same loads, and that only happens in magazine tests - well, sometimes they get it right.