I have a 04 HD crew cab 2500 16,000 miles. My mileage has never been better than 15 mpg and that was when I first got it. It has been no better than 13-14mpg all winter around town or highway and I baby the truck. Any reasons why? At $2.55 a gallon I can't afford this for long.

Where do you live? If you live in a colder climate you are burning winter fuel which degrades the fuel mileage. Do you keep the RPM's at 2K or lower? Is your truck stock (no power adders etc)? How much of your driving is in town vs highway? I get 19-20mpg with mine if I drive like a granny but when I drive like my foot likes to I get 14-15mpg. 70% highway and 30% town driving. That is all on straight #2 and also the same on B-20.

I live in CT, stock truck, my brother has a 05 and a friend has 04 both stock and around 18-20 mpg, I don't see why such a difference. The mileage has gotten worse with the miles not better.http://www.dieselplace.com/forum/images/smilies/frown.gif

I have an 04 Crew Cab, and I average 17mpg half highway and half city.I took a trip up north a few weeks ago and cruised 80mph and I was getting 18.1.
Sounds to me like somethiung ain't right.

Just got back from a round trip to Co Springs area. 1000 mi each way. Running empty (just me & wife). Beating into a 40+ mph wind both out & back... Not like the D/A much gave a sh*t about that. Got 12.4 ave out and 12.7 back (all calculated). Since I only had 1600 mi on the truck when we left and was running 80 to 85 just about the whole trip, I can't ***** much. Man!!! that sucker pulls like a train... I thought my '03 8.1/A had balls. Used 1 qt. oil. Saw a Durango with speedboat attached riding on a 32' triple axle gooseneck being pulled at about 80 into the same wind by the same truck as mine. Wife says "impressive". I replied "oh yeah!" Love this truck!!!

Rob:

Are you calculating that or reading it on the DIC?.......The DIC is all over the place in it's estimates.....actually I don't know why they put it in there if they can't get it accurate........mine reads at 13 and hand calculates to 17 empty and driving in the mountains. Reads 13 and hand calculates to the 12's towing a 5K load at 65.....my point is, if your reading the DIC, you don't really know what your getting.

I just bought my 04.5 CC/SB DMax, Allison with 23,000 mi. This week, I pulled a 39 foot toy hauler (about 13,500# with three motorcycles, full water tank and personal belongings) from Casa Grande, AZ to Eastern NY via 10-20-30-40-81. I have a 4" Banks Monster exhaust and am running 3.73 gears with 265 Toyos and an Edge Juice, which was set on 2 for most of the trip. Trip average was 7.3 on the DIC. It was calculating out to slightly less. To be fair, my driving attitude is "If you aren't the lead dog, the view is always the same." I ran 75+ in the western states and 70-75 nearer the northeast. Slowest speed on any hill was 63.5 MPH and only one truck was able to pass me and make it stick. The payback for being able to run like that is that the sound of the fuel running through the line is louder than the turbo... Just to compare, at Roanoke, I cut over to route 29 and came up 29-15 to Harrisburg. At 60-63 MPH, even though it is pretty hilly up through there, mileage went up to almost 9.

It doesn't matter if I use the dci or calculate it, they seem to be pretty close. I will bring truck to dealer and Have it looked at. Could flashing the computer help?

My DIC is coming up with about 1 MPG better than hand calculated. Averaging about 16.5 empty at 75 MPH and 10-13 MPG towing a 6000 lb load depending on speed (10MPG at 75, 13 at 65). Still dead stock at 4400 Miles.
With all the variances in MPG does the reflash have anything to do with it?

it might have something to do with the speedo being out of wack. i checked mine with the GPS on the way home today, speedo said 4 mph faster than gps.
i checked the last fillup for MPG, hand calculated at 13.6, with the DIC it was 14.7.
keep in mind i just put my Predator on two days ago ):h and have been smokin the back tires a little. I have it on the 65 hp setting. and by the way, the allison needs to do some learning again after the new setup, shifts like Censored right now, but better today than yesterday.

I have a 2004 1/2 4x4 all stock. I am getting 12.5 city and 9 towing a fifth wheel. I am going by the dic. I hope that it is off but I don't think its that off. When I bought the truck, I was getting 15.5. After the first pull with my fifth wheel the mileage went down hill from there. I drive 60 to 65 so speed and rpm are not an issue. Any help would be helpful.