richard

Just went on a trip with the 07, pulled a 7 x 12 v-nose, dual axle enclosed trailer with my electra-glide harley inside.
Over the 350 mile trip, the best I could get out of the truck was 13.3mpg.
This was running at about 70 mph no cruise. If I used the cruise, the average started to drop to about 13.1 on the overhead.

Unhooked from the trailer, and did a couple hundred miles of running around, mostly highway. average was 15.1 mpg, no cruise.

I didnt run any faster than 70-75 mph loaded or empty.
I got better mileage when I controlled it instead of the cruise, so I don't think it is because of the way I drive.

Is this the best I'm gonna get for mileage out of this truck?
If so, i'm kinda disappointed.
RPMs were in the 2200-2400 range at highway speed.
I know the truck is geared low, but this is too low.
Any ideas to improve the mileage?
The truck is bone stock, so it is not because of any mods.

Rich

benfordj

I have about 8600 miles on mine and just went on a 1000 round trip vacation; my average was 17-18 unloaded. I filled up at a Flying J on ULSD and got 19.5 at one point on a 200 mile round trip. When I pull my boat weighing in at 3500; my average is about 14-15. I have noticed with the 6 speed and 373's in the rear if I keep it around 68-70 that is my best mileage. I think things will get better when I open up the exhaust and put some more miles on her. Hope this helps.

wadediesel

I'm In the same boat. I couldn't get better than 12.5 in town and 15.5 on Hwy.
However I changed My fuel filter and added Power Service to two tanks and I got 17MPG on a 425 Mile trip. That was with no load and avg about 69MPH @1900RPM.
I still think I'm getting around 12.5-13.5 in city.

2200-2400 RPMS sounds a little high though I've heard that when you get over 2000 RPM's your MPG drops dramatically.

I have heard of guys saying they are getting 21-24 MPG HWY, I wish I knew How.

benfordj

Believe it or not... I am just relaying what my neighbor has told me. He has a 2006, 2500, QC, 2wd with 373's and a automatic tranny. He has 125,000 on her with stock Michelins by the way; cause I sold him mine when I got the BFG's and he has not installed mine yet. He has had his transmission "adjusted" by the dealer and his overhead reads 25-26 miles per gallon. When he fills up his ETA reads 620 miles for about 100 miles then starts to read below 620. He drives all highway everyday to and from work at between 70 and 75.

wadediesel

What kind of Adjustments were done?
I think my tranny needs to be serviced I might need it adjusted as well.

CD in NM

My 2006 keeps getting better and better as I knock up miles on it, so you will more than likely see this too. Pretty much everyone says the do get a little better fuel mileage as time and miles go by. I am running BFG 315's and am getting some great fuel mileage both empty and towing heavy, have right at 34K on the truck.

I think you can blame the ULSD for some of the low mileage. I just made a trip to Minnesota from New Mexico, I got LSD in most all the truck stops and my fuel mileage went up by a good 2-3 mpg's on my trip. So the ULSD is a big part of the low fuel mileage everyone seems to be getting these days.

CD

DiEseLjunKy

15-16 mpg empty when your running a brand new 5.9/g56 sounds about right to me but you won't see many people around admit to that. Anything over 63mph/2000rpms in the g56 trucks and your fuel mileage is in the toilet plain and simple. Everyone says breaking it in over time will help bring the mileage up, only time will tell, so keep working the truck if you can. Some people say less restrictive intake and exhaust, synthetic oils, fuel additives etc help but I never saw any mpg improvements from any of those things. Driving habits are a big factor with some people then again some people say no matter how easy they go mpg is low. Something as simple as driving into the wind or with it can have a big impact to but there's nothing you can do about that. There are no easy answers but plenty of snake oil.

benfordj

He said that when he was stuck in traffic his engine temp would rise and the tranny would shift weird. He took it to the shop and they adjusted the bands I think. He said that he can hit his limiter by getting on it hard and letting it shift on its own. I sorry for the hear say, but he is not a diesel head and he is just telling me what they told him.

rich

it wont get better till about 20k on it, mine does better around the 70 or 75 mph but i broke it in that way but empty the best i get is about 17

gsqhtr

Here are all of my fill ups since new, I copied this from www.gasbuddy.com. Site automatically calculates etc... The last two are from Norfok Va to Cleveland Ohio and returning. I am sure that I will be in the 19.5 range on return and that is running 70/75. I drive 38 miles round trip to work very little city driving. Taking truck to dealer today for some time of recall that basically flashes the computer etc... They are calling it an RRT. When the work is done I will tell everyone what exactly was done. This does not apply to all 07 5.9's to the best of my knowledge because is is not a "Official Recall" on website. Maybe my milage will improve.

Date Price Gallons Cost Milage Station MPG
9/3/2007 2.949 23.400 $69.01 10,188 BP
8/31/2007 2.899 27.600 $80.01 9,723 BP 19.87
8/30/2007 2.699 15.365 $41.47 9,173 Dodge's Store 19.93
8/25/2007 2.699 27.092 $73.12 8,925 Dodge's Store 16.14
8/17/2007 2.699 30.011 $81.00 8,421 Dodge's Store Y 18.60
8/9/2007 2.779 26.988 $75.00 7,964 Dodge's Store Y 15.23
8/3/2007 2.779 26.558 $73.80 7,520 Dodge's Store Y 16.45
7/19/2007 2.749 25.107 $69.02 7,050 Dodge's Store Y 17.70
7/14/2007 2.729 21.627 $59.02 6,621 Dodge's Store Y 17.09
7/7/2007 2.699 29.011 $78.30 6,225 Dodge's Store Y 18.31
7/3/2007 2.799 25.906 $72.51 5,670 Dodge's Store Y 19.13
6/28/2007 2.739 16.813 $46.05 5,239 Dodge's Store Y 16.64
6/27/2007 2.679 15.075 $40.39 4,923 Dodge's Store Y 18.79
6/21/2007 2.679 27.626 $74.01 4,675 Dodge's Store Y 16.45
6/13/2007 2.655 25.100 $66.64 4,154 Dodge's Store Y 18.86
6/3/2007 2.660 24.393 $64.89 3,637 BP Y 20.60
6/2/2007 2.630 21.368 $56.20 3,387 BP Y 10.25
6/1/2007 2.679 10.078 $27.00 3,012 Wilco Y 17.55
6/1/2007 2.650 27.832 $73.75 2,799 Dodge's Store Y 21.14
5/28/2007 2.699 15.320 $41.35 2,278 Dodge's Store Y 18.72
5/27/2007 2.690 15.200 $40.89 1,997 Dodge's Store Y 18.34
5/26/2007 2.650 25.200 $66.78 1,691 Dodge's Store Y 20.13
5/14/2007 2.630 7.560 $19.88 1,244 Dodge's Store Y 17.74
4/30/2007 2.650 27.200 $72.08 1,106 Dodge's Store Y 18.25
4/29/2007 2.590 19.200 $49.73 560 Dodge's Store Y 20.07
4/28/2007 2.650 9.702 $25.71 171 Dodge's Store Y 20.26

rustyshakelford

i just paid $120 to start running amsoil synthetic and i can tell you the motor is quieter, and it seems the mpg is going up. ill post at the end of this tank

brett

gsqhtr

I dont want it quieter, I love the noise. Yes I would be intersted in your results.

rustyshakelford

its still loud when i get on it, but to me when the motor is quieter than before, its being lubricated better...which i like!

brett

06 DIESEL

I just finished a 1800 mile trip and here are my hand calculated results for the first three tanks, have yet to fill up for the fourth.

474 miles on tank
32.003 gal
14.8 MPG

490 miles on tank
26.905 gal
18.21 MPG

503 miles on tank
29.980 gal
16.78 MPG

These are all unloaded cruise set between 70-80 depending on speedlimit. The first tank was all mountains. I had the predator set on performance/economy with the puck off.

Keep in mind that the overhead is always wrong. It is currently showing an average of 21.7 MPG for the trip.

haulin-rv

Here is what I found, if I run 69-70 empty I can get about 18 mpg. Jump the speed to 75 I drop to 14.5-15mpg. Towing depending on the load anything much over 63-65 mph and it also go down fast. I pulled a 28ft Jayco TT to Nebraska and ran 64 or so and got just over 11mpg, ran 69 back empty and got 17.8. Now I picked up a 31ft TT with 2 slides and its a front kitchen floor plan and weighs 2500-3000 more than the Jayco and to get 11mpg I had to slow down to 62mph, running 64-65 I was right at 10.