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How to get better fuel economy w/your diesel
Also what I have found is the "posted speed limit" has everything to do with mpg.
If someone lives where they hardly drive over 60-65 mph unloaded they will most likely brag that they typically get 19-20 mpg.
Someone who drives 75-80 mph will most likely be getting 14-15.
I have personally taken and compared side by side a "broke-in" 05 Cummins and a 05 Power Stroke.
What I found was at if I maintained a speed of 65 mph I averaged 18 mpg. Once I increased my speed to 75 mpg I averaged 14 mpg. SAME TRUCK... 4 MPG DIFFERENCE.
The Cummins actually dropped less mpg than the Power Stroke with the increased speed and I contribute that to the fact that the Cummins hits it torque band faster at lower rpms.
SO IF YOU WANT TO BRAG ABOUT HIGHER MPG "DRIVE SLOWER!"
(I did however talk to a guy the other day that installed a performance module called the Workhorse and says it increased his 05 PS MPG from 15 to 20. He also said towing a boat he still got 17mpg. He said he bought it at www.888luvdiesel.com)