Hey all, it has probably been several years since I have posted here. I was talking to a guy with a 6.7L cummins 4x4 saying with his tune/delete blah, blah, blah he gets 27 mpg. I asked him if that was hand calculated or what he read, and he claims its calculated.
I have a stock 05 with a 6-speed, 3.73 gears, and I can barely break 17 mpg. I believe my truck could do better, but I don't believe this guy at all. What is the best fuel economy we can reasonably squeeze out of our trucks?
thanks!

 

My stock 2003, equipped like yours, averaged around 14 mpg mostly in town, and always hand-calculated...My current ride, described in my sigline, gets around 13 mpg under the same conditions...I have yet to figure out why someone would spend that much money on a truck, then "delete" many of the components that make them work well to begin with...From my reading, this leads only to increasingly more problems followed by the waste of even more money...The only thing I ever "deleted" from my two Dodge/Cummins were the mufflers and everything behind them......Ben

 

I have seen a high 21.5 in my '89 Ramcharger with a 12V, 5 speed and 3.54 gearing. I even just got 20 MPG on the money on it over 430 miles of around town driving when I topped it off 3 days ago. Meaning 21.5 gallons over 430 miles.

IIRC I saw 23 or so on my old 12V motor in my '85 crew cab with 3.07 gears and a 5 speed. That truck will do 80-82MPH at 2000RPM though, so the low RPMs really help with good mileage.

27 MPG on a 3 rd gen? I don't believe that.
Hand calculated only counts when the person doing the "calculating" can do math....

 

Your friend is not telling the truth.
My 5.9 is 17 ish depending on my right foot. I drove a 6.7 for work the best I could eek out it was 15.

 

beacause 7-12 6.7s were a steaming pile of dung. If they were worked hard, and I mean HARD, they seemed “ok”.... but if some poor sap like most of us wanted to maybe “drive it to work” on a daily basis, some short trips etc.... UNHAPPY! I’d delete that era of CTD ALLLL DAAAAY LONG!

 

MY 2005 2wd auto gets about 20mpg on the interstate long haul trips running 75mph. At 65mph it has got 22.5mpg. Averages 16-18mpg in town driving. My truck is a 2wd 4 door short bed. All stock .


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My 05 2wd auto gets about the same numbers. Speed has everything to do with MPG!! I once ran 90 miles in foggy conditions on the Interstate and without towing and traveling about 50 mph in the cool early morning hours and got 26 hand calculated. When i realized the fuel guage was not moving much I got off at my destination exit and topped the tank again to do a hand calculation. The mpg computer calculator on these vintage trucks is not accurate. It always tells me I'm getting 2 or more mpg than I am actually getting with a hand calculation. Pulling my 31 foot 5th wheel I get 12 to 14 depending on speed, headwind and terrain. Of course my 05 is a 5.9 unmodified with only the catalytic converter still installed. All motor vehicles get better mpg driving 60 or under as opposed to running 75/80, However running 60 when everyone else wants to run 80 is dangerous. I suppose speed limits have now become just a suggestion and are rarely enforced anywhere.

 

2005 with AUTO, usually gets 15 MPG round town... On the highway, i can go anywhere from 20-23 if i keep it in the 65 range. My tires probably cost me a mpg. These trucks if you can run them at 60mph,,, you will get excellent MPG,, EXCELLENT. !!!!
I keep my 285's air low, like 60 front, 50-55 back empty... The stock Michelin radials kill it on the highway,,, i think my best with them was 24MPG at 65, hand calculated.