First post, MPG question 6.7 Cummins

[JayTX]

Hi all,

Purchased a new 2017 2500 with the diesel engine and manual transmission back in the day. The truck has never averaged more than 20 mpg. Lately it seems to be doing even more over long drives to 15-16 mpg. Even lower running around town.

It's all factory setup, no heavy cargo on the bed and I drive it very conservatively.

My brother and several other friends get better mileage.

Routine maintenance is kept up and there's no Mx lamp lit on the dash. The truck runs fine, pulling an 8k# trailer and goosenecks and what not with no issue.

Any ideas on whether the manual transmission is causing an mpg penalty or might there be something wrong?

thanks,

 

[Bigskyroadglide]

It's definitely not the manual transmission unless you are running it without gear oil. I would suspect something like a frozen brake caliper on one of the wheels, a sticking parking brake or something causing increased rolling resistance.

It could also be engine related, a slipping clutch or some other power robber but doubtful it's the transmission

 

[Fake-Account27]

22 Is the best I can get on the highway and MPG starts to decrease exponentially once you go above 65 mph. It seems to get the best MPG around 55 mpg, maybe 60. Makes sense given air resistance increases drag exponentially. However my Pacifica minivan can still get 28 / 29 at 70 on the highway.

Around town I do a lot of short trips so 13 or 14 is quit normal on a tank. Towing is between 10 and 12 depending on the conditions.

How many miles does it have?

 

[06 Dodge]

Outside of mechanical problems your right foot and the speed you drive have the biggest impact on your fuel mileage, in fact manual trans normally get better mileage then an auto trans. Also what size tires are the tires, if bigger then stock they will lower fuel mileage. BTW when was the last time you took it out on a run with a moderate load, if it has been a while it may just need to stretch it legs for an hour or two.

 

[Toddbigboytruck]

I need to talk with someone about the l/10km or mpg. Towing ver not towing I have a travel trailer about 7600 lbs and well on my 1500 321 rear I am 32L/100km or 7.36mpg. So when you are not towing with your Cummins you get what 20 mpg. What do you get when you are towing Hunt went from Hershey P A to Ontario can and cost a lot driving to Tampa in December. I want to really run the number and want real life not text book number any help will be appreciated

 

[Toddbigboytruck]

I bought a 2500 but was stolen before I got it and told myself I didn’t need it but I do think I do

 

[jejb]

I need to talk with someone about the l/10km or mpg. Towing ver not towing I have a travel trailer about 7600 lbs and well on my 1500 321 rear I am 32L/100km or 7.36mpg. So when you are not towing with your Cummins you get what 20 mpg. What do you get when you are towing Hunt went from Hershey P A to Ontario can and cost a lot driving to Tampa in December. I want to really run the number and want real life not text book number any help will be appreciated

Mileage is dependent on a lot of factors. My 18 2500 CTD with 3.73's pulled 21.5mpg hand calculated on the one long road trip I've taken with it without a trailer. It was about 14 hours each way. And I was on the gas. It was almost all interstate with 70 or 75 mph limits, and I locked the cruise control a 9mph over the limit for the entire trip. I was very happy with that.

Towing my bass boat this summer on a mostly interstate haul of 12 hours at 72mph netted me 14.1 hand calculated both directions.

Towing my 7k Vee nosed enclosed trailer at 70-75 is pretty much a 10-11mpg thing. A lot better than my 3/4ton gassers did, but still kind of thirsty. I read some crazy high numbers from other folks towing bigger trailers/RV's, but they are driving more in the 55mph range. I just can't bring myself to do that on an interstate with 70-80mph limits. Seems like an accident waiting to happen to me.

Good luck with your decision, and sorry to hear about the stolen truck.

 

[Toddbigboytruck]

Thank you. Ok so how I read 21 not towing. And towing like 10. Thank you for your direct and honest. It is tiring reading some posts what they are saying is impossible again thank you and as for the truck was to pick it up on Friday they flatbed stole it 1 am that day All the gps stuff was not activated so they couldn’t track it

 

[06 Dodge]

I need to talk with someone about the l/10km or mpg. Towing ver not towing I have a travel trailer about 7600 lbs and well on my 1500 321 rear I am 32L/100km or 7.36mpg. So when you are not towing with your Cummins you get what 20 mpg. What do you get when you are towing Hunt went from Hershey P A to Ontario can and cost a lot driving to Tampa in December. I want to really run the number and want real life not text book number any help will be appreciated

What year Cummins, is it a HO or SO 2500 or 3500, what gears does it have all of it along with who well you can control your right all foot factor into what mpg it will get, with my new 2022 empty the best I have gotten is 22, I think your best mpg numbers when towing will be keeping RPM's between 1500 and 2100 aka 55 to 65 MPH once you go up 70+ mpg numbers drop, so if you want to save $$$ all you can take it easy, stay in the left lane and let the others speed on by as they are not paying the fuel bill you are...

 

[68PowerWagon]

Thank you. Ok so how I read 21 not towing. And towing like 10. Thank you for your direct and honest. It is tiring reading some posts what they are saying is impossible again thank you and as for the truck was to pick it up on Friday they flatbed stole it 1 am that day All the gps stuff was not activated so they couldn’t track it

Are you talking in code? I can't understand most of your posts.

 

[Gr8bawana]

Are you talking in code? I can't understand most of your posts.

Well of course you can't understand his posts, look at his user name

 

[Toddbigboytruck]

I am trying to get real numbers ((mpg)( American ). Or ((l/100km)(Canadian) for a diesel vrs. Gas in towing my travel trailers I am still wounding if I should get a diesel 2500

 

[Toddbigboytruck]

Well of course you can't understand his posts, look at his user name

How do you not under stand metric system.

 

[Fuel35 67]

The diesel will tow anything heavy, better than a gasser. It’ll get better mpg’s because it’s more efficient. Go with a diesel!