Hypothetically, what is max fuel efficiency for the 5.9?

[Wferenz]

My current truck has averaged 17. 98 mpg over 36,043 miles (last 2,147 miles with a Smarty Jr on #1).



Best mileage on a CTD was my 98. 5 (same configuration as below). I live in CA and recieved one of the first 24 valve trucks. Towed a 3,000 lb boat/trailer to northern WA and back without any concern for mileage and got 30mpg. About a month later I received a letter from the DMV stating that I had to return the truck to the dealer for 'reprogramming' because Dodge did not recertify the 24 valve engine... . they simply used the 12 valve test results. The DMV stated they would not allow me to re-license the vehicle unless the reprogramming was completed. After reprogramming I lost 9 mpg on the same trip without the boat!



Wayne

 

[RMalone]

Mileages ARE quite variable with these trucks. But I think you could say the following.

1. Driving habits make a huge difference. Speed, acceleration etc.
2. 12 valve and early 24 valve trucks seem to get the very best mpg.
3. 2wd trucks do better than 4wd.
4. If you can average, tank to tank, 20mpg + in any CTD, your doing pretty good!!

 

[BDeMartile]

My overhead was dead on from new and then there was an upgrade flash and it started to read about 1. 5 high from hand calculations. i let the mileage run up without any resets and at 8900 miles the overhead shows average 19. 3. Hand calculated shows 19. 2. This is overall city hiway 5ver towing you name it mileage. Its a keeper.

 

[HOBrian]

Best I ever got was 24. 3 drving about 57mph in steady moving traffic, of course my over head said 28. 9

 

[mhenon]

I was getting 22mpg at 65mph in CC. When I installed a tonneau cover the mileage went right to 24mpg+. I read that a bed cover was good for a 10% improvement and mine was right on. Tires and air pressure are another biggie. Here's more info:updated FAQ on Ram MPG improvement (long)

Mike

 

[BPowers]

I have a '04. 5 2500 and I drive everyday about 50 miles back and forth to work for now. I hardly ever drive it in the city. I've learned that when I drive around 70 mph and keep the R's low I will average between 17-19 mpg. When I do drive in town it goes down to about 15 mpg. These number are from the overhead but they are very close to when I hand calculate it. Only maybe 2 mpg off. My truck only has 72k on it and I'm hoping as it keeps breaking in that the MPGS will keep going up! Now after saying all of that. Is there any mods that anyone would recommend to improve the MPGS?

 

[KIKER]

I wish my '07 5. 9 would get that! I've got 21,000 miles on it in a year and am getting 12-14. Crew cab duallie, auto, 4X4, 3. 73 gears.

 

[PRout]

Best overall Ive been able to obtain is about 18. 5 avg. Have tried lots of different combos (injs, boxes, programmer, intakes, tires, driving styles, you name it) and this truck seems to get about the same mileage no matter how I drive or set it up (with exception being mud tires cost about 1 mpg). Never seen over 20, but it is a 4x4 and runs a bit heavy with extra fuel. Pretty much have given up at trying to break the 20 mpg mark. Runs good though. .

 

[hdtrukn]

Hey BPowers

What kind of tires do you run and what pressure in them.

I picked up my 04. 5 in S. Carolina and did not get better than 17. 5 coming home, checked the pressure and they where at 42psi. I run 65/70 in them and that gained me almost 2 miles per gallon.

Thats the only thing I changed. So FAR.

 

[steved]

IMHO, the best combination (in stock form) for mileage is a 95/95/96/97/98 truck with 3. 55s. You get the benefit of the better aerodynamics and the low RPM fuel sipping 12-valve.

Of the Cummins I've ran, my dad's 95 2500 4wd 12-valve with the auto and 3. 55s, got the best... he regularly topped out at 28mpg (hand calc'd) on the highway. My 99 2500 4wd 24-valve with the auto and 3. 55s was the next best reaching into the mid 20s.

 

[Crunch]

After reading these posts I believe that 30MPG is possible for those that are currently getting the 20+ MPGs on a regular basis. For someone like me, 25-28 MPG on a regular basis seems doable. The design of the engine shows that it is possible. Wferenz's post about the reflash is a pretty good indicator that there is a hidden foot up the hiney of our trucks: Government. It would be interesting if someone got hold of a 2003 Cummins 5. 9 and trimmed it out with their own ECM to see just what it could do. Imagine the rage across the country if all the CTD owners had proof that the government was shagging them for a potential 20%-30% of their fuel economy while diesel prices are going through the roof, and the quality of the government-mandated ULSD fuel is in the toilet. Makes me mad just thinking about it.

 

[steved]

After reading these posts I believe that 30MPG is possible for those that are currently getting the 20+ MPGs on a regular basis. For someone like me, 25-28 MPG on a regular basis seems doable. The design of the engine shows that it is possible. Wferenz's post about the reflash is a pretty good indicator that there is a hidden foot up the hiney of our trucks: Government. It would be interesting if someone got hold of a 2003 Cummins 5. 9 and trimmed it out with their own ECM to see just what it could do. Imagine the rage across the country if all the CTD owners had proof that the government was shagging them for a potential 20%-30% of their fuel economy while diesel prices are going through the roof, and the quality of the government-mandated ULSD fuel is in the toilet. Makes me mad just thinking about it.

I'm really surprised someone hasn't used a Cummins ECM on a CRD to see what difference it would make.

 

[HCanales]

I have 4. 10 gears and I thought about installing 3. 73, would that make a difference? I'm getting about 25ish according to my overhead. Of course I like hittin the reset button and tricking myself in thinking I'm getting good mileage. Currently though I'm only going 55 mph to get 25ish mpg,I'd like to go a little faster and do the same in mileage.

 

[Crunch]

I have 4. 10 gears and I thought about installing 3. 73, would that make a difference? I'm getting about 25ish according to my overhead. Of course I like hittin the reset button and tricking myself in thinking I'm getting good mileage. Currently though I'm only going 55 mph to get 25ish mpg,I'd like to go a little faster and do the same in mileage.

You're the first person I have heard say they were getting 25MPG on the 4. 10. I was about to say, "Heck, yes" when I read your question about the 3. 73. But if you are getting 25MPG--verified by hand calculation, with the 4. 10 I wouldn't change it unless you just don't like that pumpkin. This is one of those times where geezer wisdom makes a lot of sense: If it ain't broke, don't fix it.

 

[HCanales]

Calculated I'm averaging 23. 3mpg. I think that 3. 73 would help but its about $1000. If anything it may help with wear and tear. Of course if a guy installed lock out hubs that would help even more with wear and tear. The problem with that is $2000+ for the conversion and I don't think they make hubs for a dullie. I don't know if I can justify the expense yet.