The faster you go the worst your mpg will be. I don 't really calculate my mpg as what does it really matter. I need to pull a heavy fiver around so I got the tool to do it. That being said I had a 2012 dually ram previously. I know this truck gets better mileage around town. Both of the trucks have 4:10 rears. The 2013 and up will get better mileage according to the advertisements but remember your load, your speed the terrain and how big of a head wind your in will increase or decrease your mileage drastically.