For reference - 2006 Dodge Ram 2500 4x4 Cummins gas mileage - hard numbers

[Z-Michigan]

I'm pasting below the first 15,000 miles of driving on our 2006 Dodge Ram 2500 4x4 with the 5.9L Cummins turbodiesel. Virtually any tank below 16mpg was partially or entirely pulling our 3-horse slant trailer - 4800lbs+ empty and add 12-1300 lbs for each horse, and it sticks up 2' higher than the truck cab for good measure. Any tank over 18mpg was usually most or all freeway travel, often at 70+ mph. You can see our best tank in this batch was 19.5mpg and our average, not towing, is in the 17-18mpg range. Mostly my wife is driving this. There are no mods nor anything special, though I do keep the tires at the recommended towing pressures - if I remember correctly this is 60psi fronts and 70psi rears. The overall average of this whole set, calculated based on averaging the 3-tank averages that I use to watch for any long-term changes (and not displayed here) is 15.7mpg, which, again, includes a lot of time towing the 5k+ trailer.

Based on how things were in 2006 - with diesel and gas being the same price or diesel even being less, and with diesel engines being reliable and about a $6k option - I would buy diesel again. Based on how things are today, with diesel being 30-50 cents more/gallon and the engine costing $8k, if buying new I'm not sure I would.

Odometer Reading Gallons Purchased Date Trip Mileage Trip MPG
75 0 01/26/06 n/a n/a
100 20.646 01/26/06 25 n/a
243 9.84 01/28/06 143 14.5
368 7.661 01/31/06 125 16.3
586 15.127 02/11/06 218 14.4
1020 26.113 02/17/06 434 16.6
1307 17.812 02/19/06 287 16.1
1593 18.7 02/25/06 286 15.3
1929 23.718 02/27/06 336 14.2
2420 27.068 03/02/06 491 18.1
2733 16.97 03/03/06 313 18.4
3130 27.466 03/06/06 397 14.5
3330 14.52 03/08/06 200 13.8
3620 22.502 03/11/06 290 12.9
4120 27.225 03/12/06 500 18.4
4472 18.712 03/15/06 352 18.8
4553 5.312 03/18/06 81 15.2
4925 23.15 03/23/06 372 16.1
5121 13.814 04/01/06 196 14.2
5400 20 04/08/06 279 14.0
5700 21 04/08/06 300 14.3
6084 24.308 04/15/06 384 15.8
6517 25.801 05/08/06 433 16.8
6876 26.985 05/11/06 359 13.3
7096 17.095 05/15/06 220 12.9
7539 25.821 05/21/06 443 17.2
7867 23.248 05/25/06 328 14.1
8164 22.846 05/26/06 297 13.0
8510 23.958 05/26/06 346 14.4
8893 25.413 05/27/06 383 15.1
9058 12.41 05/28/06 165 13.3
9360 22.277 05/28/06 302 13.6
9695 22.066 05/29/06 335 15.2
10010 22.323 05/30/06 315 14.1
10512 27.38 06/08/06 502 18.3
11035 26.874 06/13/06 523 19.5
11207 12.996 06/14/06 172 13.2
11614 24.646 07/05/06 407 16.5
11997 23.044 07/16/06 383 16.6
12319 21.789 07/20/06 322 14.8
12517 14.317 08/12/06 198 13.8
12918 23.741 08/24/06 401 16.9
13105 16.268 09/04/06 187 11.5
13438 18.123 09/09/06 333 18.4
13723 16.372 09/19/06 285 17.4
14127 22.748 10/01/06 404 17.8
14382 13.718 10/04/06 255 18.6
14642 15.822 10/08/06 260 16.4
14997 22.077 10/24/06 355 16.1

To answer the obvious question, I don't have the chart ready for tanks after the last one. I have the receipts with odometer readings on them, but haven't gotten around to entering the data since it's my wife's vehicle.

 

[john_bud]

Hmmm, pretty close to what my duramax gets. Although, I probably drive it more like an old lady than your wife!

Average MPG Hours DATE HOURS GALLONS MILES Actual MPG
17.602 8.5 5/7/2007 1488.4 16.4 59344 21.0
17.615 8.2 5/14/2007 1496.6 16.2 59673 20.3
17.623 8.8 5/23/2007 1505.4 19.0 60035 19.1
17.640 7.7 6/4/2007 1513.1 14.4 60346 21.6
17.653 8.4 6/15/2007 1521.5 18.1 60711 20.2
17.666 8 6/25/2007 1529.5 14.7 61013 20.5
17.675 7 7/3/2007 1536.5 12.2 61262 20.4
17.685 6.8 7/12/2007 1543.3 14.8 61558 20.0
17.697 9.8 7/19/2007 1553.1 18.0 61917 19.9
17.675 7.1 7/24/2007 1560.2 21.8 62226 14.2
17.682 5.5 7/30/2007 1565.7 10.2 62432 20.2
17.688 8.7 8/4/2007 1574.4 16.4 62744 19.0
17.675 5.7 8/9/2007 1580.1 17.0 62997 14.9
17.691 7.4 8/12/2007 1587.5 16.9 63353 21.1
17.709 6.4 8/12/2007 1593.9 20.0 63773 21.0
17.721 6.6 8/14/2007 1600.5 18.3 64139 20.0
17.738 9.9 8/17/2007 1610.4 17.8 64518 21.3
17.755 8.9 8/19/2007 1619.3 13.3 64813 22.2
17.760 4.5 8/20/2007 1623.8 13.2 65067 19.2
17.774 6.9 8/22/2007 1630.7 18.0 65439 20.7
17.789 6.3 8/22/2007 1637 22.2 65887 20.2
17.795 7.4 8/30/2007 1644.4 14.5 66169 19.4
17.790 10.8 9/9/2007 1655.2 24.2 66581 17.0
17.796 5.4 9/14/2007 1660.6 10.3 66785 19.8
17.809 11.3 9/25/2007 1671.9 23.9 67261 19.9
17.819 11.5 10/9/2007 1683.4 23.0 67709 19.5
17.819 13 10/18/2007 1696.4 22.4 68107 17.8
17.822 4.1 10/25/2007 1700.5 8.0 68262 19.4
17.825 6.3 11/1/2007 1706.8 13.0 68506 18.8
17.813 7.1 11/12/2007 1713.9 20.8 68830 15.6
17.801 8.4 11/24/2007 1722.3 24.8 69224 15.9
17.793 10 12/7/2007 1732.3 21.9 69581 16.3
17.790 9.4 12/18/2007 1741.7 19.2 69911 17.8
17.785 7.1 12/31/2007 1748.8 14.5 70152 18.2

Average vehicle speed is 40.1 mph.


Sorry if the columns get messed up.



I also fully agree that were I to buy a truck today, the extra cost of a diesel would not provide me with any benefit. Especially as the new ones don't get as good of mpg's with all the emission stuff. {Heavy Sigh} Progress! Harumph!!!

jb

 

[Z-Michigan]

Great info, and hard numbers really help. It looks like the DMAX is treating you very well. I'm not sure we've ever broken 20mpg, certainly not on a regular basis. My wife drives very sedately 99% of the time. Presumably you have the Allison 6-speed auto? We have the 4-speed auto that was the only auto offered on Dodge/Cummins through 2006. Two extra gears might help!

I think the 2005-06 MY diesels are going to be worth a lot more in the used market than the 2007-08 MY diesels - but we're planning to keep this one at least 10 years, maybe more. The reported fuel economy with 2007+ diesels is not at all encouraging.

Incidentally, someone will eventually note most of these tanks were probably before ULSD was common. That's true, but in the diesel Jeep Liberty I also had (and don't miss - Liberty CRDs are unreliable, unengineered junk IMHO) I saw absolutely no difference in mpg before and after ULSD, with the same detail monitoring of its mpg.

 

[john_bud]

Z,

Yes to the alison, no to the 6 speed. It's the 5 speed version. Standard 3.73 gears with limited slip and 4x4. I don't honestly know the impact of ULSD vs LSD on MPG's as it came in last year with winter fuel. My highway mpg's seem to be pretty much the same.

This graph is a little old, (it's a PIA to remember how to pull the graphs out of excel). It is total miles / total gallons and updated with each fill. When the total miles were small, the impact of towing or running empty on the highway was pretty easy to see!


You can clearly see the impact of colder temperatures and the winter fuel. I make a effort to idle as short a time as possible. As soon as it smooths out, I'm gone. Heck, you expect cold fingers and cold tushie in a Wisconsin Winter. Besides, the fuel used in idle mode is nearly the same used on the highway at 65 mph, why waste it?

One thing to note on this graph, the improvement in economy from new to now (70+K miles) is about 1 mpg. They do get better, but not much.

Hope this data is interesting...

jb

 

[Renze]

your truck uses more fuel when empty, than my Volvo 850 2.5 TDI pulling a 2 horse trailer... Ever thought of buying a smaller truck ?

 

[john_bud]

Renze,

Oh come on now, rub it in!

Meet some of the US anti-polution standards and see what your mpg's drop to.

jb

 

[cschlaps]

Just posted in a similar thread. I have an 03 Dodge Cummins 5 speed short box quad cab on 35" tires. Not exactly sure on the rear axle ratio, but it's in high 3's. No chip or any other mods. 135k miles.

All highway at 55-60mph (below 2000 rpm) and I can squeeze 20+mpg out of it. My calculations factor in the tire size difference.

If I'm doing a mix of street and highway driving, 17-18mpg is typical.

It's a great truck, and even with the higher diesel prices these days, I'd still prefer it to a gasser. I've heard highway numbers in the 12-14mpg range for those driving the hemi version of my truck. 17-20mpg is a significant increase. Factor in the better longevity of a diesel with the excellent resale values, and it seems like an easy choice (to me, at least...I drive a lot though).

I used to have a GMC with a fuel injected 454 - a great truck and motor indeed, but 10-12mpg was it, and 8mpg while towing anything. I'll take the torque, efficiency, longevity, and resale of the diesel any day.

Z-Michigan - where are you at in MI? Do you belong to TDR?

Chris

 

[Z-Michigan]

I'm about 15 miles SW of Lansing. If TDR is the diesel register, I'm aware of it but don't belong. We run the Dodge stock and have no plans to modify it, and haven't had any significant problems with it. It's actually getting its first comprehensive maintenance (all fluids and filters) done as I type this.

My BIL had a 1996 Chevy 454 1-ton dually 2wd for a while. It towed well, but yes 8-10 mpg was the normal range, and anything over 12 would have been a miracle. He didn't need such a large truck so he sold it and now has an F150.... but I digress.

Renze, I hear you, but it's not really apples to apples. My wife does actually carry 3 horses fairly often, and once you have a 3-horse trailer you're way above anything you could tow with a car. And as John said, when you get the new diesel emissions requirements, watch your mileage plummet!

 

[cschlaps]

I've kept mine stock as well (except for the larger tires), but highly recommend the TDR board (Turbo Diesel Register) for troubleshooting. It has come in very handy for me, on a number of occasions.

Enjoy your truck!

 

[neucam]

It seems diesel pickup fuel numbers are dropping, when the Cummins first appeared there was reports of 27 highway and 20 pulling a trailer. Now 20 empty is a norm, and drops fast after that. As a comsumer I would ask for more from your dealer, now the diesel mileage is getting very close to a gas engine. The diesel tractors still are effecient because of no EPA or Gov regulations. YuK