Will be picking up my 07' 5.9 2500 Q-Cab 4x2 Short-WB tomorrow or Monday. What is the average mileage everyone with 4x2 is getting? I'm sure it will be much better then my 08' 6.7 that I traded in. Need honest numbers. Has anyone removed the cat and had improvements? Thanks.

 

I hand calculated 19.8 mpg (my last tank), and this was with some hauling (mainly my mower and equipment, and a 16ft load of wood 20 miles).

On a full tank with no hauling I was seeing 21mpg last summer.

Towing my travel trailer the best i got was 17.4, about 16 when i was in the hill country with the cruise set on 70mph.

Worst mileage was 13.5mpg, this was pulling a 42 foot float back home relieving a damaged truck. Had about 8k of drill stem loaded from an H&P rig. A little heavy for my trucks suspension but the engine drug it like a mule.

I would say ideally 18-20 mpg is what you can expect. Some claim as high as 24mpg, only 24mpg i have seen was on my overhead, never was able to hand calculate that.

 

The 305/555 motor with NV-5600 is the best for mileage with 2WD. I can always trip plan for 24 mpg/highway loaded or empty, rain or shine, traffic or no traffic, etc the past 14,000-miles. This is at 1750-rpm/58 mph. I have seen tanks above this as well. There are others with the same mpg on the same combination. Automatic drops it some. Any speed above 60-mph does the same (although on trips of 300-miles or less the time-savings is practically nil). A headwind of ABOVE 5 mph begins to affect mileage (I believe it takes a 3-5 mph tailwind, stern-quartering or directly behind to negate the worst aerodynamic drag).

If you want to find your mileage potential:

Plan a 200 mile roundtrip on the Interstate, where, you run out 30-miles and top off fuel. Begin record keeping from this point. Engage cruise control for 58/9 mph at end of entrance ramp. Do a turnaround about 100 miles farther out and return in same fashion (take only a short break that engine doesn't cool off). Return to same fuel island & pump and refill in same manner (first click off seems fair). The number you record won't be too far off from a long-term test if winds are mild.

 

Unloaded normal driving (70 mph, 2k RPM) I'll hand calculate 19.2mpg combined driving consistently no matter what time of year. Lightly loaded towing (about 7500 pounds) on 2 occasions, once in October 2008 and again October 2009 I hand calcualted 15mpg, mostly highway, that was about 4 tanks. All mpg's at same speed, and towing with cruise on. 54k on truck last time.
Best I've ever seen was in September 2008, 4 adults in the cab and bed loaded with luggage under tonneau - hand calculated 24.2 mpg! Filled up in Sevierville, TN and drove back home to MS Coast on a tank of fuel.
You can throw all those numbers out the window over 2k RPM!
I have a straight 5" exhaust & saw no difference in MPG over stock exhaust. I do see decreased EGT's though.

 

Finally got a few tanks in. This is all city+highway. Tank 1: 19.8; Tank 2: 23.9; Tank 3: 22.1; Tank 4 20.6 and that is it so far. Not to bad IMO. First tank was a little low due to me liking the excelleration on this 2wd. This is all hand calculated. Very impressed with the 07' 5.9 engine even with the incylinder EGR crap. Read were a F1 Helix 2 cam will add honest 2mpg to what I'm currently getting. Not a bad truck for daily driver. But my 12v is still my favorite. Thanks for all the replies.

 

With everything in my sig, Smarty on 3, doing
65 on highway. 25 mpg hand cal.
I just made this truck into a short box, with weight
loss, it will be interesting to see if I gained any more