i have a late 2000 3/4 ton 4wd, 6 speed stick with the 5.9 and have 335,000 miles on it. i'm still getting around 18mpg on interstate. was looking to buy a newer one but everyone i talk to says that the 6.7s get bad milage and had trouble with turbo. just trying to get a little more info before i make my decision

 

https://dodgeforum.com/forum/dodge-r...s-section.html

 

Welcome to DF.

03-04 Cummins get pretty good mpg ~20ish, 04.5-07 mileage goes down due to new programming 14-18. Early 6.7's had alot of issues but "most" have been sorted out. Best bet is to dump the EGR and DPF and that usually solves 98% of the problems.

 

throw some rv275 injectors on it, and if you're running 4:10 gearing, change it to 3.54 gearing...you will see 20+MPG and have some extra power!

or you can dump a ton of $$$ into it and lose fuel economy like me but have a huge grin on your face every time you touch the throttle.

a smarty tuners timing will help a bit on economy too..also gives a good boost in bottom end power.