I have an 06 with 9500 hwy miles and the mpg is at 10.5 to 11 if i drive 80 and 12.5 if i drive 70. I keep hearing everybody talk 18 to 21 mpg's but where is it? I wanna know this, HOW MANY MILES ARE YOU GETTING PER TANK? And thats a 35 gal tank. I am at 350 to 375 and have never been over 400 miles per tank. I think if this dont get any better i might look for another duramax. My last one was at 19 to 22 mpg but rode like Edited by Admin.

 

I now have almost 13000 miles on my 06. I'm getting from 17 to 19 mpg. I have stock size tires and 3:73 gears.

 

I get 15-16 mpg since it was new....i'm sure it will get even better after break-in.

 

I hate to tell you. But a 06 duratrash ain't going to get you any more mpg than your dodge. Now back to the dodge. I don't wan't to tell you you are driving your dodge wrong, but when I made the same switch you did, I had to drive my dodge diff. than the duratrash. I try to keep mine in as high as gear as possible, making sure low rpm's. Also the other two things that I have found that contributes to higher mpg is the outside temp. (make sure your truck is warmed to temp. as quikly as possible) and the quallity of the diesel fuel. I use power service whight in the winter and power service silver in the summer. I add it every tank full. I also run the freeway no faster than 65 mph. Once again less rpm's. The more rpm's the more fuel period. These cummins engines do not like rpm's Also if you havn't towed something real heavy for a long tow. Do it. It will help the aid in the break in and help mpg, make it have more power.

 

I ran 410 miles on my very first tank of fuel, and when I filled up it took 30.5 gallons. It came out to 13.44mpg.

Maybe you should have the dealer flash the computer with the most current update for it? Some guys here have been seeing 2-3mpg increase after that.

 

I have an 06 and never got that bad. I started out 13 to 14 and it has inproved every since. I get 18 to 19 empty now on the open road. I got an avarage of about 14 mpg pulling an empty car hauler from Phx to Kansas Ctiy and back with a 43 ford on the trailer. I ran 80 mpg in AZ and New Mexico and 70 mpg in Oka. and kansas. Take it back to the dealer and see if they can check that computer for you. I had one update on mine that helped a little. Mine is 4X4, 2500, 373 gears and stock tires.

 

I have the latest flash update, i think it was 6.0.6. It was done 2 weeks ago for none start issues but the flash before that was the backup horn blowing one. And anyone can slam everything about a duramax they want but truth is they get better milage than my dodge. Even said so in diesel power mag. But i still wouldnt trade for one with my crummy milage.

 

The truck I will be getting shows 18 miles on the odo, and the overhead mileage says 14.2. I know that doesn't mean anything, but thought I would post it.
I hope I get one that gets good mileage.

 

Recieved my new 06' 3weeks ago now has 2500 miles on the clock. I put on 315 bfg's the first day i got it. they are perfect with the new six speed. with the truck just three days old. we left for Memphis, 625 miles away from home. I was getting 18 mpg at 70 mph (GPS speed), once i hit Tenn. speed limit changed to 70 , so i set the cruise on 76. MPG slowly dropped on overhead to around 16 mpg. Now that ive gotten home, my mileage has been about 18-19 mpg. Figured on GPS mileage. Keep the rpm's around 2000 or below, and you should see an increase. Didnt see if you had larger tires or not, but they always seem to help, in my case anyway. This is my fourth CTD, ive learned alot over the years about these trucks. Someone said these engines dont like rpm's. I disagree, these things will pull all day at 2500 rpm's, and never break a sweat. but high rpm's do lead to poor fuel mileage. good luck.

 

Just did some hand calcs. on the hiway at 77mph i got 17mpg. Over head was reading less? Long trip with many resets.

 

I just did mine.....30 gallons and got 490 miles.......16.333

 

I'm up to about 15 mpg now with 90% city driving and about 4000 miles. My wife took a 1000 mile trip to pick up her grandmother and got about 17 mpg. She said she had the cruise control set for 75 mph the majority of the way.

 

From south fork, CO to Amarillo, TX around 400 mile trip, i used 16.2 gallons of diesel. Thats around 24.6mpg. Believe me or not, oh well. On the highway i never get less than 20

 

ive got 6800 km (4250 miles) on the clock, o/h reads 19.9mpg, and i currently have 1160 km (725 miles) on this very tank of fuel, fuel light came on last night. Last tank was 1080 km (675 miles) and i put in 134.04 litres (35.4 gallons). I always fill right too the top of the filler tube, and on the hwy never exceed 65 mph. It takes me about 45 more minutes too get where i am going, but i almost double my range, so i think it is worth it!!

 

I've had my truck for just over 3000 miles now. I've got the manual trans and 3.73 diff. The best I've seen for mpg was about 17.3. That was running very gently and empty on fairly flat roads between 60 and 65 mph.

I've found I get a huge variation in mileage based on how I drive it. Driving style alone can kill several miles per gallon. Sometimes I just can't resist feeling the amount of torque these motors put out.