What are you guys seeing in the 6 spd autos? A better question would be what RPMs are you guys at? Im not sure of the ratios in the trans myself. I would think if you had 3.73 it would be below 2k...... (hopin fora double overdive here haha)

 

4.88 rear axel 3/4 city(San Francisco Bay area traffic) 1/4 highway (65-70) 12.4mpg

 

15 city 18 hwy

RPMs 1650 at 65mph

 

15-16 city and 18-20 highway, the best I ever got was 22 highway at 61 mph and about 1700 rpm.

 

RPMs are very low but mileage is too. You would think it would be really high but it's just not the case. I get 13 city/16-18 highway with a best of 20 hwy under perfect conditions at 65mph.

 

The mileage is so low, because of all of the new emissions components that the 6.7 cummins has on it. the dpf filter basically chokes the engine, and the computers control so much of the emissions in the cylinders now, that no matter what rpm your running, your mileage wont be what it used to be with the 5.9

 

2000 rpm is 81 mph, mileage is not what it should be , but I find it not much lower than my '01 while towing.

 

12 city 15/17 highway empty 10.5 towing a 13500 lb fifthwheel trailer in fifth gear and 1700 rpm but i only have 1700 miles on the truck

 

My dually gets 17-18 on the road In mixed driving i get 13-14 If I am nice pulling my toy hauler i can see 11 ( Nice is 60 ) Usally pull 70-75 mph about 9.5 trailer weighs 15500 loaded

 

Im getting about 10mpg city (or lower) and 12-13 HWY at a mix of 60-70mph on average... The highest Ive gotten while towing a couple of jet skis was 12mpg at 60-65mph... Cant remember what my RPM's were at...

 

bigvick and I get about the same.......WHY?

 

Burner, that is some crappy mileage for sure. I'd take it to the dealer because there has to be something wrong with it. If they couldn't help, I'd take it to another dealer. If they couldn't help, I'd take it to a used car lot...

Good luck.

 

keep these post coming. Im in the market for a 6.7 and getting rid of my Dmax. Iknow i wont get the same mpg the the power and torque will be better.

i really want to get as much info as possible

 

@ 70 MPG on the HWY I get 17-20 MPG

 

Right off the lot at 42 miles (9/22/07) I filled up, made a 550 mile trip doing 65 mph with no load and no towing, temps were 65-70F, running on flat ground and cruise control so there was minimal impact from "driving style". Hand calculated mileage was 17.8. Gears are 3.73 with 6 speed 68RFE.

Since then it had the O2 recall and I believe the AV flash. First week of June this year with about 14,000 miles I made another long trip using same driving style for over 1400 miles. One tank was 18.8 and two were 19.3 mpg.

I had the AX flash in mid-June and made a highway trip in July of 1500 miles had my mileage at 18.5 with same conditions. During this trip my entire DPF/Nox exhaust plugged up and I was running nothing but highway speeds.

New exhaust and turbo flush in mid August with AY flash update and mileage has never been over 18. Waiting on new turbo, new EGR system, and oxygen sensor update and hope it gets here before exhaust plugs again.

Am I happy? It's been all downhill since the AX flash and the parts are on backorder. Good luck.