Fuel mileage

[NBigelow]

My truck has almost 13k miles on it and should be well broke in I've pulled a 25k+ Load from Co Sprigs to Phx after pulling up a 10k trailer up there 1800 mile round trip. then I did it again a couple moths later but only 22. 5k on the return trip.

granted pulling that much isn't going to get me fuel milage although on the way back the second time I averaged 9mpg or so. considering the 4. 10 gear and only goin 65

I feel the truck should be getting more than 14 empty the dealer told me that it should get about 20 at about 10k but i'm not getting close even though I baby it and try to keep it about 70 to keep the Rpm's down.

I drive truck for a living currently and I thing 2500 rpm's at 75 in the big hole is way to fast it should only be around 1800 at most the cummings can pull a lot at those rpms and get better mileage. I wish I had 3. 73's but with the weight it helps to get started with the 4. 10 they need to add another gear so the motor dosn't have to work so hard.

Bottom Line I think the dealer was over stating it a bit. and he said 20 with the 4. 10's HAHa

Has anyone tried an overdrive transmission and had any luck?



by the way the truck pulled that 25. 5k load back and didn't go under 4th gear of 50mph cummings 600 rocks :-laf

 

[doldenburg]

Good luck. A few on here will claim unbeliveable hi mileage. I'm at anound 26,000 mi. now and if I BABY it empty it will pull 16-17 mpg at 55-65 mph. nice puller tho. od may help you but will take a very long time to pay you back.

 

[RMarkey]

I haven't even towed enough in one complete tankful to figure it, but empty, w/ th 4. 10's and the auto transmission, I get an average of 11. 7mpg mostly hwy, little in town driving, so good luck. I seem to have the worst mileage that I've heard about though, and despite what you think, I AM babing it! Try to keep under 65 on the hwy is what I do to keep it UP around 11. 7mpg. I can get 12's if on flat ground hwy around 50/55mph!

 

[klenger]

RMarkey: With those milage numbers, it sounds like your truck is borken. Injector(s)?

 

[XJSuperman]

I have yet to tow anything significant with my '04. I'm at about 12,000 miles and I'm seeing 17 city and 21 hwy. I usually do a near 50/50 split and have been avg about 18. 5 with that. I don't drive it into the ground but I far from baby it.

 

[J&LRam]

the 600 motor isn't gettin' the fuel milage the 555 does. Thats one reason we see a big difference in fuel milage claims of our 3rd gens. Why the big difference?? I'm sure there are some on this forum that can give some reasons.

I do know that auto trannys, big tires and 4. 10 gears won't add up to good fuel milage... ... ... ... . JIM

 

[drewRoberts]

I'm averaging around 17-18 unloaded. I generaly stick it to 70 on the highways and only push the throttle to the floor on rare occasions. what my mileage is loaded I'm unsure. I havent pulled a load for a distance to see where I stand. One of these days I'll chain a tree to my truck and pull it down the road to see what happens (I'm invisioning blue lights in my future :-laf )

 

[mbadger]

I don't have 9,000 miles on mine yet, but two weeks ago I drove 700 miles round trip and averaged 20 mpg. Mostly interstate, but in the mountains of Western Montana. When I pull a load it goes down a lot as expected. I drive under 65 all the time. I hope the milage improves when I get a few more miles on it with the prices of fuel. Have a great day.



Mike

 

[caseyd]

I just turned 25,000 miles and get an average of around 13. 5-14 even.

(this is mostly highway and taking it easy)

I got the TSB done for mileage (15,000) and the first tank hand calc to 15. 5 mpg. since then 14 is the best I can get!

I have not checked mileage with a heavy load (Afraid to).



Before some one asks, I get the same mileage with the 315's as I did with the 235's. With mostly highway miles they make up for the 4:10 gears.

And no, I did not get the odometer recalculated for the 315's I just multiply my hand calculation by 1. 088 and that gives me the correct mpg for the difference in tire dia.

 

[joeyou]

I've been doing some experimenting on my 04. 5 600. My weekly commute is 500 miles and I've found that going over 65 mph really eats into the mileage. Prior to my experimenting, I averaged overall 17. 9 mpg. This was driving 72-75 mph on the freeway. I've experimented with driving slightly under 65 mph (cruise on 63-64) and strictly adhering to the speed limit in the 55 mph zones. Doing so, I've been able to raise my fuel economy by 1. 5-2 mpg. Two tanks at around 19. 6 and one at 20 mpg. I had both a 95 and 99 cummins previously, and one thing I've found on these new ones is if you go above 65, expect the mileage to drop a lot. Also, they are pigs in town and when towing. I think part of it is that with all the extra power, we use it and enjoy it without really realizing just how much more we are using as compared to older models. I do think the fuel economy potential is not a high on these new rigs, but it certainly is not as bad as some make it out to be. I guarantee that guys getting 14 empty have their foot into the throttle, hit the brakes a lot (a major killer of fuel economy), and do a lot more city driving than they admit.

 

[caseyd]

My overhead is always with in 1 mpg of my actual hand calc and

I can set the cruise on 55 going down the highway clear my overhead and within 3 miles it will settle in around 14. 1. When I clear it while driving it will

start out at around 18 and drop to 14 something within a couple miles.



I've done some testing of my own, I took a 400 mile round trip to the hunting lease drove 60-65 mph (in the slow lane) 3 stop lights each way. Leaving the stop lights I eased up to cruising speed. Sat idle no longer than a min. or so each time and My hand calc after the trip was 13. 9.



I'm telling you, I've tried my best to get a 15+ mpg tank with no luck!



If I could find a 400 mile all downhill highway I may be able get 15+.



I finaly said the **** with it and started driving it like I stole it and it

only drops my mpg to around 12. 5-13.

 

[NBigelow]

Yea but what gear ratio do you have? is it 4. 10 I do a lot of country driving at 60-65 and cant top 14 plus the 4x4 and dually adds wait so don't tell me I must have my foot in it.

 

[caseyd]

NBigelow



It looks like I finaly found someone thats getting the same sh***y mileage as me!

I love the truck and the power but I would happily trade some of the power for a couple extra MPG!

 

[RMarkey]

I went to dodge today and had them look at it and they said everything was good so I went ahead and got the re-flash so we'll see if it helps any.

Caseyd I know exactly how you feel, down hill around 55 I can get high 14's. I don't really get much of a chance to get into it, I take the level freeway to and from work and don't really do anything else, so very little around town.

When I do get into it the mpg doesn't drop much at all, which is nice, but I continue taking it easy hoping the mpg will be better if I'm good. I'm used to gassers where that works, can't seem to break the habit I guess.



I'm gonna install a AFE pg7 and exaust soon, maybe that'll help some, porb not w/ my luck. Either way, the truck is still fun to drive!

 

[Diesel4Stan]

With my 555 2003 LWB Auto 4. 10 unloaded (2 months new to me), using dino oil, all highway driving, I got 17. 7 mpg with the tail gate down (6 wks ago).

With syn oil on 1 tank, I did mostly (85% guess) highway, I ended up with 18. 2.

I'm taking another road trip this weekend (same as before) so I can get a "similar" comparison. I'll have a couple of light wt. items in the bed (<25 lbs), so I'll keep the tailgate up this trip. If its true that I should get better mileage with the tailgate up (this topic is always up for debate) and running syn oil, I'll be one happy camper if I get 19-20.

The mpg was hand calc and an easy foot runnin' at 73 mph (cruise control). I would guess that the 600/610 will lose 1 mpg (comparing to a 555). I'll reply with the results in a few days.

 

[Diesel4Stan]

The second trip with the tailgate up, all highway, I averaged 18. 0 mpg. The 0. 2 mpg is close enough to say it was basically the same mpg. Three things I did differently than the first trip (I remembered this on my way home) - added 10 psi to all 4 tires (front 60 psi, rear 50 psi), tailgate, and I bought diesel at a different station. Plus there's always the factor of "how far up the neck did I add diesel?"



Bottom line, I believe the syn oil helped improved my mpg.

 

[torqmakr]

I have noticed that if you coast alot(less braking) you will better numbers. Try it out it seems to work.

 

[Dieselnerd]

My 2nd Gen with 4:10 gears averages 18. 5 mpg combined city/highway. Towing my fifth wheel (around 13K) it gets around 10. I am taking delivery of my 2005 in a little over a week. It also has 4:10 gears. I am hoping it will get close to the same mileage as my current truck since all the weights will be similar and the gearing is the same. As soon as it's broken in I'll be posting the results. I sure hope it's not one of those fuel suckers...

 

[martion007]

I got a 2wd 03 4. 10 6 sp. 555 I just turned 300,000 this week I use it to deliver campers. So half the time I'm loaded. I always monitor my fuel milage as it's money in or out of my pocket. Loaded with a camper I always pull at 65 and I get 12 to 14 empty I run from 65 to 69, I always get from 22 to 30. That is no jive. One of the most important things is tire pressure 80psi When I got the truck on the front door it was written 55rear and 60 front But that lowers fuel millage 3-5mpg So keep that tire pressure at 80psi

 

[Diesel Dually]

I picked up an '05 3500 4x4 QC SRW LB 6spd (NV5600) 3. 73 from Tomeygun a little over a month ago. My mileage started at 14. 5 and by the time I had about 1500 miles on it I was getting 17. 5. I have also noticed that if I get above 70mph the mileage drops like a rock. So far I have very little city driving, about 98% highway. This truck is an early '05 and the reflash has not been done. The overhead has been about 0. 5 to 1 mpg optimistic so far. I haven't been able to tow anything yet, but hope to get a gooseneck hitch installed soon (just need to decide which one)...



I still have my '96 3500 DRW 4x4 regular cab auto 3. 54 gears. My mileage with this truck averages about 18 on the highway, though I have been able to squeeze out a couple of 20mpg tanks if I am super nice with it. This truck seems to drop above about 73mph. Towing around 14K I get about 13. 5mpg average, with a mix of city / highway driving. I have some transmission goodies and have turned up the pump a bit on this truck, also a 4" exhaust from turbo back. This helped my towing mileage ALOT. I was down around 10mpg before the mods while towing, and around 17 empty on the highway. Seat of the pants comparing a third gen auto 600 (test drove) and my '96 tells me they are close to the same power,'96 seems better down low (torque converter?) while the 3rd gen auto seemed better above 2200rpm.



In any case, my mileage so far with the new truck is very close to my 2nd gen. I hope my mileage will continue to rise, especially with the price of fuel, but I'm getting what I expected at this point.



If fuel prices keep going up I may start making a little biodiesel but ONLY for the '96 since I don't want to give DC any excuse to try and void the warranty on the '05.