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2025 Cummins MPG Compilation

PyroJoe

PyroJoe

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Going to pick up my 3500 DRW tomorrow. I'll update as I begin to gather data myself. I'll have a ~1500 mile trip to get it home with some towing mixed in, as well.

I'm sure I'm not the only one who wants to see real-world highway MPG figures for the new Cummins and new 8 speed (with straight #2 diesel). Most of what I've seen so far has been people driving 20 miles here, 70 miles there, and only telling what their lie-o-meter says. Not very accurate...

I'd like to see hand calculated mpg values only, please. Please post the following info:
-2500/3500/4500/5500
-4x4 or 2WD
-Tire size (ex. 235/80R17)
-R&P Ratio if not 3.42
-Cab & bed configuration. Also include SRW/DRW if 3500. (ex. CCLB SRW)
-Odometer
-Avg speed
-Number of miles driven
-Your hand calc'd MPG

-Throw in your towing numbers if you want - I'm sure someone will be curious about that. Be sure to include your:
-Trailer type
-Trailer weight
-Which transmission gear you're running in
 
I'm going to update this #2 post with my return trip info from Mark Dodge to Nebraska. Once I've broken the engine in, I'll update with my max mpg. I'd like to find out what setup gives the best MPG for these trucks before I swap on my new 35's (to help decide if I can justify regearing).

The mpg went up nicely throughout the 1500 mile trip home.

1st tank
-3500
-4x4
-Stock 235/80R17
-CCLB DRW
-507 odometer
-55mph for first 100 miles
65-80 for last 407 miles
-464 miles this tank
- Lie-o-meter said 17.0 mpg
Hand calc'd is 15.9 mpg

2nd tank
-724 miles odometer
-Averaged 75mph nearly the whole trip
-17.1 mpg

3rd tank
-1340 mile odometer
-80-85mph and had a regen, so this tank is kind of irrellevant
-Lie-o-meter said 17.6
-Actual MPG = 16.8
 
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Picked mine up in Houston on April 3rd. Drove back to Yuma (1200 miles?). Did a lot of it about 80 mph, give or take a few. It’s a 3500 CC DRW 4wd Long bed. Empty at those speeds was almost 15 mpg, hand calc. . I have always done hand calcs and made mental notes, as the meter in my ‘03 was way off.
As of today, I hit 5505 miles. Mostly loaded/Towing. I made a trip back to Washington (1450 miles) to have Torklift install their hitch and camper tie downs. I towed the wifes car (Hyundai Santa Fe) on my trailer. Again, pushing the speed limits, I was running about 12.5 mpg. Towed the trailer back to Yuma with about a thousand pounds on it, and still stayed about 12.5 mpg. Loaded my 10’ Lance on the truck, and just got back today from a 7 day romp through the mountains of Az. With just the camper and no trailer, I’m getting 10-10.5.
Surprisingly, the mpg computer is matching the hand calculations on this truck.
Hauling the camper on this thing is a dream compared to my ‘03 3500 srw.
 
PyroJoe said:
Going to pick up my 3500 DRW tomorrow. I'll update as I begin to gather data myself. I'll have a ~1500 mile trip to get it home with some towing mixed in, as well.

I'm sure I'm not the only one who wants to see real-world highway MPG figures for the new Cummins and new 8 speed (with straight #2 diesel). Most of what I've seen so far has been people driving 20 miles here, 70 miles there, and only telling what their lie-o-meter says. Not very accurate...

I'd like to see hand calculated mpg values only, please. Please post the following info:
-2500/3500/4500/5500
-4x4 or 2WD
-Tire size (ex. 235/80R17)
-R&P Ratio if not 3.42
-Cab & bed configuration. Also include SRW/DRW if 3500. (ex. CCLB SRW)
-Odometer
-Avg speed
-Number of miles driven
-Your hand calc'd MPG

-Throw in your towing numbers if you want - I'm sure someone will be curious about that. Be sure to include your:
-Trailer type
-Trailer weight
-Which transmission gear you're running in
Click to expand...
Looking forward to your info on this. Still trying to decide between the 6.4 or the Diesel yet. Thanks
 
Are you seeing big differences between the computer and your hand calculations? I hand calculated my 1500 and my 2500 for the first dozen fill ups or so and it was never more than .3 to .5 off so I stopped and just used the computer.
 
Sure enough, the lie-o-meter was 1.1mpg optimistic the first tank. The is consistent with TFL's results as well as every single other vehicle I've ever owned. I updated my 2nd post.
 
Whats the "Pro" $5 get you over the free? I've always just kept a pocket book in each vehicle to track gallons, price, and MPG, and any service. Would be nice to make it shareable for others to see tho.
 
PyroJoe said:
Whats the "Pro" $5 get you over the free? I've always just kept a pocket book in each vehicle to track gallons, price, and MPG, and any service. Would be nice to make it shareable for others to see tho.
Click to expand...

Gets rid of ads, which I'll gladly pay for. Nothing more annoying to me than getting an ad for that harbor freight tool I was just looking at right after I close the browser when doing something unrelated. You also get better charts and your data outside of just basic fuel and maintenance is also backed up into the cloud, you can attach photos of actual receipts etc.
 
poorman_pw said:
Gets rid of ads, which I'll gladly pay for. Nothing more annoying to me than getting an ad for that harbor freight tool I was just looking at right after I close the browser when doing something unrelated. You also get better charts and your data outside of just basic fuel and maintenance is also backed up into the cloud, you can attach photos of actual receipts etc.
Click to expand...

Photos and PDF's.

ALL my maintenance info and records for all vehicles goes into aCar(Fuelly).

I couldn't figure out a better way to track DEF so I just setup another vehicle.

You can import excel or CSV and many other app's data files. Records can be exported as well.

Since it's also cloud based data (you can make local backups) you can install on all your devices and share across them and the web app.
 
T143 said:
My truck is a 3500 single wheel
Tub is 6.4”
4x4 Laramie
68RFE
Stock diff gearing
295/70/18 Maxxis Razar AT 811
Randys valve body and deep sump
Banks air horn and boost tubes
Stock airbox

Caravan
Urban X-Terrain 18.9 foot
Tarre 3070kg
ATM 4390kg
Click to expand...
Sounds like a pre-2025 truck. I made this thread for the new 2025 8 speed diesels.
 
3,300 miles in and the best tank I've seen was 19.1 on a 100 mile trip.
I've been playing with cruising speeds from 50 all the way to 85 mph. I'd pick one, reset the MPG meter, and let her eat for 10-20 miles and see where the best RPM was.
After repeating this on a flat elevation road several times to make sure I wasn't just driving downhill and skewing results, I believe 56mph which is 1300 RPM in my truck, to yield best MPG. 31.8" tires, .64 OD
2500's and SRW 3500's will have taller tires, so your speed will be a bit higher to hit 1300 RPM. Let me know if your results match with 1300 working best for you! I've gotten the instant mpg to read steadily between 23-25 doing this.
 
Finally completed my long Vegas trip, hot-shotting there and back to pick up my plasma table.
2609 miles
249.25 gallons
10.5 mpg avg for whole trip

Pulled an empty 20' bumper trailer there (2 7k axles). Pretty solid 11mpg on way there.
1,100 pound table loaded up for the way back.
Average speed starting out thru Nebraska and Colorado was 78-80.
Once I hit Utah, I never dropped below 80 the rest of the trip. Kept it between 80-88mph. Came back thru Wyoming.

Not real impressed by this. I did the exact same trip with the LBZ duramax, same trailer, only difference being I towed an 8k LB suburban back. And the dmax did over 2mpg better! BUT... I was slowing down on the mountains with it. With the Cummins, I set that cruise to 84 and she didn't break a SWEAT! ZERO slowing down on grades. ZERO over heating issues despite outdoor temps of 95 in Denver to 107 in Vegas. ZERO braking issues. Freaking awesome. Just needs to go on a diet now so it can get better mpg.


20250728_171103.jpg20250728_171113.jpg
 
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PyroJoe said:
Finally completed my long Vegas trip, hot-shotting there and back to pick up my plasma table.
2609 miles
249.25 gallons
10.5 mpg avg for whole trip

Pulled an empty 20' bumper trailer there (2 7k axles). Pretty solid 11mpg on way there.
1,100 pound table loaded up for the way back.
Average speed starting out thru Nebraska and Colorado was 78-80.
Once I hit Utah, I never dropped below 80 the rest of the trip. Kept it between 80-88mph. Came back thru Wyoming.

Not real impressed by this. I did the exact same trip with the LBZ duramax, same trailer, only difference being I towed an 8k LB suburban back. And the dmax did over 2mpg better! BUT... I was slowing down on the mountains with it. With the Cummins, I set that cruise to 84 and she didn't break a SWEAT! ZERO slowing down on grades. ZERO over heating issues despite outdoor temps of 95 in Denver to 107 in Vegas. ZERO braking issues. Freaking awesome. Just needs to go on a diet now so it can get better mpg.


View attachment 88243View attachment 88244
Click to expand...

If you have time to post a little bit about your trip or details about the trailer setup that you towed in the "tow" section, I have a few questions. Thanks
 
Andy2025_3500_DUALLY said:
-R&P Ratio if not 3.42 = 3.42 is the only choice

-Your hand calc'd MPG = 9.9 mpg

-Throw in your towing numbers if you want - I'm sure someone will be curious about that. Be sure to include your:
-Trailer type = 5th wheel, 42' long, H- rated tieres
-Trailer weight = 14,700 empty, 15,900 loaded
-Which transmission gear you're running in = it's an automatic tranny, so 8th most of the time and 7th up hills
Click to expand...
We have 3.73 & 4.10 options - they're just expensive AF right now. About $1000 for the rear R&P only, not including setup kit.
9.9mpg is pretty respectable for a 15-16k trailer! I have a feeling these trucks will just get 9-11mpg no matter what they're towing.
Did you notice it dropping out of 8th pretty easily with that weight when you hit a hill? At 5k lbs, I only got it to drop out if I was really hammering on it in the mountains.
 
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