I recently bought a new 2007 Dodge Ram 2500 6.7 diesel pickup. I just returned from a 3700 mile trip from Texas out to Arizona and back pulling my trailer which has a GCWR of about 7500 pounds. Before setting out I reset my trip odometer and fuel mileage readouts on my overhead console to zeros. I always used tow/haul when towing, and I usually drove around 60-65 mph. When I got back I found that I had averaged just 10.9 miles per gallon of diesel for the entire trip. That included a lot of miles doing day trips from our campgrounds where I was not pulling the trailer. This surprised me because from reading other posts from diesel drivers I was expecting much better mileage. A few months ago, pulling the same trailer up through Colorado and New Mexico mountains up to South Dakota and back, but using my old Chevy 1500 gasser, I had averaged 10.7 mpg. Am I doing something wrong? After this Arizona trip my truck has just 6100 miles on it, so is it just not broken in yet? From your experience what should I reasonably expect to get, mpg-wise, with my setup?

 

IMO, 10-12 towing is probably about correct. I believe you will see an increase in your unloaded mpg but not until the engine has significantly more miles on it. I'll bet it climbed the hills allot easier than the old gasser though.

 

Lots of variables , besides how you drive , the most important is gear ratio [ including tires ] , they drop the option for the 3:55 a few yrs back , so you should have 3:73s or 4:10s .
From what I seen others talking , a min of about 12 mpgs towing with 4:10s & about 15 mpgs with 3:73s , I seen some get about an added 5 mpgs with both if everything was good , have you asked dealer yet ?
Have you done anything to truck , including changing tires ?

 

Give it some time to break in. My 5.9 has got about 1000 miles more than yours and I see the fuel mileage improve every fill up. Youll break in faster than me too just by pulling the trailer around too because I havent had a chance to tow anything yet.

Also don't put much faith in the overhead display. I have an excel spreadsheet where I calculate my mileage and such. I also wrote an equation where I enter what the overhead is saying and it calculates the % error between actual mileage and overhead mileage. I think the closest it has ever been is 11% over optimistic.

Just give it some time and run some hand calcs for your mileage. Hopefully it'll improve with some time.

 

Not sure how the 07's work on tow haul, but if it was locking out any gears, you may have been turning higher RPM's than intended, thus burning more fuel?

 

I think the main issue is that it takes 20-30k to break these in. Until then, they are a liitle less. Air your tires up to the max as well.
I am not sure if the 6.7's do the sam as 5.9, but I read a test where they are similar.
Of course, always travel with a tail wind!

 

Thanks for the input so far. I forgot to say that I have the 6-speed automatic transmission and altho it doesn't say on my sticker I am almost 100% sure the rear end is 3.73. Throughout the Arizona trip the tachometer showed a pretty consistent 1600-1800 rpm's at 60-65 mph.

 

I have got a friend who has a 6.7 in a reg cab manual truck with a flatbed and tool boxes and a fuel tank on it. He is only gettin 15 unloaded no trailer. I hope it can get better for ya'll with the 6.7's. I'm gonna stick with my old 5.9's for a while.

 

A buddy of mine has the new 6.7 and he just took it in for a recall, something to do with the EGR?? He said that he was getting poor fuel mileage and the dealer told him that the recall should help with the mileage. I dont know, but worth checking into.

 

there are many posts on this site as well as other sites-of 6.7 owners complaining about their mileage. i see the same posts on the d-max and ford sites too! seems to be that the new "emission friendly"" diesel engines are getting anywhere near the mpg as the "older diesel engines".

 

I just had the latest recall done. They replaced the o2 sensor and flashed the computer. It sounds alot better now. Has a little more rattle when it fires up. Mine used to sound funny when starting kind of sounded like a 6.0no, but not now. Seems to be more responsive down low and no more light throttle stumble. I've only driven about 25 miles after I got it back and according to overhead the mileage has gone up .3 from 15.7 to 16. Maybe see if it needs to have that done that may help. When I pull my trailer, it weighs about 6000 lbs, I get between 10 and 12 hand calculated. Not as good as my '00 but way better that the yukon. It would only get about 8.

 

When you get some miles on your truck you ought to post that spreadsheet info here and share it with us. Hardly ever see a decent mpg thread where someone goes to that much trouble keeping track of things.

 

Running around town empty I get 12-14 mpg, on the highway I'm getting 16-18 mpg. When I tow my boat (7500 lbs) I get 10-12 mpg. I have 7K miles on my truck so far.

I would say you are right about where you should be mileage wise for a 6.7 with the number of miles you have. You may see some improvement as you get more miles, but don't expect it to be huge. The biggest reason for the reduction in mpg between the 6.7 and 5.9 is the larger cubic inches of the 6.7 (350 versus 408) and all of the emissions systems. Currently, the average 6.7 regends several times per tank of fuel, possibly more often if you do lots of stop-go city driving and idling. Whenever it's in regen, its injecting additional fuel into the emissions system and reducing your mileage. Keep in mind this type of mileage is equal to or better than what the new Ford's and Chevy's are getting. I can also say this is about what my Ford 6.0 got, so I'm quite happy with the mpg and towing power.

When you are in tow/haul it does not lock out any gears. It does use a different shift profile to keep the engine in the ideal towing rpm range, it will downshift very aggressively with the exhaust brake on and it does keep your torque convertor locked until a lower rpm to maximixe exhaust brake functionality.