I have been looking for information on what sort of fuel milage I should be getting because I have never had this poor of milage in a diesel truck. Every forum I read ends up giving suggestions for deletes or mod chips and I am not interested in messing with my warranty at all. Looking for honest feedback on stock 6.7L milage.

My on-board computer tells me I am getting 11.3 MPG. I have 42,000 miles and I do about 70% highway (rarely over 70 MPH), 30% city and occasionally (3 times a month) tow a 12' utility trailer. I usually keep about 800 lbs. of tools/canopy in the bed. The best milage I have seen is 16.3 on a 350 mile, all highway trip.

I really feel like I should be getting better milage. I don't drive it hard at all. I have had several check engine lights, all fixed by dealer. Had to replace the turbo around 20,000 miles and most other lights appeared to be exhaust issues. Is there something wrong with my truck?

What sort of milage are you seeing out there?

 

Nope. It's all messed up just the way the EPA mandated it.

When I bought my 08, it had about 45k miles on it and the overhead said the average was 10.2 mpg. I thought the newer trucks did a little better. What ring and pinion ratio do you have?

The reason you're getting turbo and exhaust problems is that you're not driving it hard enough. The VGT and EGR systems clog up with soot if you don't blow it out. It's better since they've reprogrammed things to allow regen at idle.

But regen = dumping fuel, so you'll never get the kind of economy that you did out of older trucks.

 

To be honest, I don't know what sort of ring and pinion I have. Is there an easy way to check?

 

2 things. You need to drive it hard, these trucks need to work. If you do the deletes your mileage will come up. Mine before 15mpg unloaded. I would get 8 towing. After best tank 19.5 Haven't towed yet. IMO deletes are worth the money. Your truck will thank you as well.

 

On my 08, I averaged 12.5 between Seattle and Sarasota, with a ~14,000+ pound trailer hooked up. That's up to Rushmore (10% grade, iirc) and then over to Denver too, so there was a lot of hilly terrain.

That was after the deletes. I wager my gross combined was in the 22k range - 12,700 on the trailer tires, and the truck had three people, a bunch of gear, and 2000+ pounds of tongue weight.

I have no complaints about 12.5.

On the return trip, I got about the same in my current truck, a 98 12 valve 2wd.

Both autos. 3.73 in my 08, 3.55 in my 98. 6-speed auto in the 08, 4-speed auto in the 98.

The 08 was MUCH happier towing that load. Better tranny, more power, better gearing.

Unloaded in my daily driving I average about 15 in both trucks, but my foot is a brick. I enjoy the thrust.

 

'07.5 -12 were/are terrible for fuel economy and yes, you can thank the government. Ford and Chevy were just as bad until they started using DEF around '10 which allowed them to significantly cut down on regeneration cycles and still meet EPA standards. Because the Cummins I6 was slightly ceaner, coupled with the fact Chrysler had some built up environmental "credits", Rams didn't have to add DEF until '13.

I just recently drove my '14 from Florida to NY and averaged just shy of 24 1/2 mpg, non towing but with a few hundred pounds of gear. I consistently get 4-6 mpg better than my buddy with a ' 13 Powerstroke with DEF setup.

Regearing might get you a mpg or two, but it would take forever to recoup the cost of the ring/pinion, install kit and labor.

Your only real options are to delete (and kiss warranty goodbye) or trade up to a DEF truck. Of course the latter option gives you more smog crap to have to worry about failing and giving CELs...

 

Thanks Hammer, that's great info. I think I will be giving up the warranty very soon.

 

Update: I took my truck in to Dodge and asked them to figure out what was wrong with it. 3 days later, with no CEL, they decided to replace the EGR. It was still running poorly so they have decided to replace the DPF. I love our government! After they replace the parts under warranty, I will go through the delete process.

 

I highly recommend keeping ALL of the emissions crap in storage. Should you ever need it, you could easily spend $5000 or more trying to replace it.