wife gets right around 19mpg every tank ... 13k on motor ... no long trips yet ...

 

In my daily commute, 62 miles round trip, with 70% highway and 30% in town driving, I average 18.6mpg.(pen and paper)

On a 283 mile trip this weekend, 65mph top speed, and going thru 5 towns(with stop signs, etc) I averaged 23mpg.

Last summer pulling my 5er, I averaged 11mpg.

I have 17000 miles on the engine.

 

Let's see what kind of MPG we get on our 600's once they break-in.

 

No, reflash will not increase fuel economy. However, there will prolly be a reflash for that in the future, but don't get your hopes up (maybe 1-2mpg).

I find it interesting that the engine has gone from 180hp to 325hp using the same displacement, has 1/3rd of the emissions, and you still expect it to get the same fuel economy.

The changes made for emissions have come at the cost of some fuel economy.

Put some big tires on it.

 

I would think that reduced emmissions is a result of higher combustion efficiency; leading to more power and higher economy. Unless a portion of the energy from the fuel is being used to reduce emissions.

 

Well I travel the country racing dirt bikes and havent seen numbers like I see in here. I also understand that when people say (in town driving) it could mean people in Stillwater Oklahoma running 45 mph for 3 miles in between stoplights with not much traffic, or kansas towns that are flat and able to maintain 45 mph through town, not to mention that most of these people are running 4x2, not 4x4, they will add everything in there signature except that part, but they still want to compare trucks, its apples and oranges to me. I bought the biggest most dependable truck I could get and am happy with it, I just dont see how a dually 4x4 4-door truck with an auto can get 20mph! lets just be friends and I will still wave when I see a big truck out on the road, I just am not interested in a 4x2 or what they get for fuel economy, I will keep my 15 mph average.

 

I would be happy with 15 mpg. I like the idea of having the power when you need it but I also like knowing I can get better mileage than a 1/2 ton gasser when I want to. My problem now seems to be that I am forced to give up MPG to be 50 state emission compliant. When I was a ford owner, I got sick of hearing all of that 20 to 25 mpg stuff and now I go with Dodge/Cummins and it looks like I might have picked the wrong engine cause i'm only getting 12 to 13.

 

I'm not bummed yet about my fuel MPG. Still under 1,500 miles and just got over 17mpg on this tank. 70% hi-way. It just gets better and better for me. Once over 10,000 it will yield over 20mpg.

 

You think a Ford or Chevy doesn't have to meet the same emissions and will get better fuel economy? Think again. All Companies had to comply with these standards starting in January of 2004. At least your Cummins runs, unlike alot of the Ford 6L's. Maybe you would like to change out the various EGR components on your Ford and/or Chevy (Cummins was able to do it without EGR). How about the crank case vent that they have? It returns the crankcase air into the intake system right in front of the turbo. I saw one the other day that had 13,000 miles on it and already the compressor wheel was covered in black.

So, which engine would you have picked?

 

Do you have any idea what exactly is causing the large drop in fuel economy? I understand it is a different type of fuel system but why so much different. What do you think the "possible reflash for mpg" you referred to would do to help mpg...timing, fuel, etc.

 

First of all, nobody is really getting 20, let alone 25 MPG with a dually, 4X4, automatic. Maybe a 4X2, nv5600, SRW, with some bigger tires to lower the final drive ratio.

The fuel system is the same except for some minor injector changes. Just like you said, the injection timing and fueling quantity plays a very large part. Beyond that, I am not exactly sure what would be changed in the calibration to increase fuel economy. It would probably be more of an "optimization" to put the emissions right on the edge and gain back some fuel economy.

I am sure they could make a truck that did get 25mpg if they didn't have to worry about one upping the competition all the time. It may only tow 10,000lbs and wouldn't be very fast to 60mph, but it would get great fuel economy. Gotta love those marketing execs and their horsepower wars.

 

I am scheduled for the reflash for hesitation tomorrow thanks to member v12xke pointing me to the TSB number. This dealer said that new trucks are automatically reprogrammed at 3000 miles for break in purposes....anybody ever heard that one? Also have an oil leak at the bellhousing cover.

 

Never heard of that one. There is no "break in" calibration. Maybe he's talking about the HEMI.

 

Not to instagate a fight with anybody, but most people on here own a D 2500 single wheel 4x4 with a handshaker in it. That is one reason they get better mileage. Then there are some that have a slush box and do pretty well with the D 2500 4x4. Then there are people that have Duallies 4x4 with the handshaker that do better than those of us with slushbox Duallies 4x4 like me. Then you have the 2 wheel drive catagory 3500 dually that probably do better than any 4x4 dually, and last but not the least 2500 2 wheel drive that smokes everyone in the fuel mileage DEPT. Choose your catagory and remember some engines take longer to breakin I don't care what anybody says. I have seen it own my own truck. I was concerned too about mine, at about 22,000 miles mine finally got better. Mine only got 12 to maybe 14 mpg. when new, now at about 26,000 miles on the ticker I get about 17 mpg. at 65 to 67 mph. FWY. speed. When I run at 75 to 80 mph. I get about 15 mpg. this is empty. When pulling something about 10ish ain't to bad for a big truck that can pull my butt or a small dozer or anything in between. and pull going up a bridge that is pretty steep or hills for that fact. Try that in a gas rig see what the mileage is. Give it time it should break in. Enjoy your truck and good luck.

Sittenbull

 

I was thinking the exact same thing as you, dwhite! I thought the engine could only be more fuel efficient because they were able to get better emmissions with no EGR. I still don't understand the apparent decrease in fuel economy.