mine is a 08 2500,6spd manual trans, w/3.42:1 gears, it gets in town 14.5 to 16 depending on how i drive it , highway is 17.5 to 19 depending on how fast and wind,and has been as low as 11.5 towing a o4 super duty ford dualy one ton 4x4 on an open trailer at around 11,000 lbs. at a very fast speed, most towing i do with it is a 28ft. open car hauler that wieghs 2,600lbs empty, and it usualy will get close to in town numbers when towing a car at normal highway speeds... 13 to 15? I have been thinking about trying to do a mpg test with me driving to get better mpg in mind and see what I could get out of it calculated , as most of my numbers listed above are an average over many fill up and different drive cycles, to me thats whats important not what i can get once ,but how it is normaly....and yes my over head is always a little off but not to bad.