LOL, yeah, there are some interesting MPG claims on here from time to time. My wife says men lie about sex and fuel mileage and I told her I've never lied about fuel mileage. When I hadn't had my 6.4L for long I saw a guy in a rest area and he had a DRW 6.4L almost the same as mine and was pulling a small travel trailer that must have weighed about 3000 lbs. So we speak and I ask what king of fuel mileage he's getting and he says something like 18 MPG towing. At that time I'm thinking I get around 7.5 so I'm listening to what he has to say. He goes on to tell me that if I keep the boost under 10 PSI I'll get that too. Now, had I done that I would still be trying to get out of that rest area, cause my truck isn't pulling my 5er anywhere staying under 10 pounds of boost. Good luck reaching the 12 MPG mark.

 

18 MPG on a truck this size EMPTY would be a good day, even with a ford 6.7 diesel.
I realize everyone like fuel economy, but you can't just add a tuner and get 20+ MPG with big tires.
If you want good mileage, go buy a lowering kit, run tire pressure to the max, maybe even 19.5 wheels, and drive 55 MPH.
If those things don't sound very fun, keep filling it up, stop worrying about mileage, and forget about it.

There is no excact % of fuel economy gain with a tuner, because stock fuel mileage is influenced by the DPF regen cycles, and driving habits.
Nobody seems to drive the exact same way, and exact same routes all the time, you're mileage will vary, not even arguable.

If someone drives all highway, all stock, and goes to an offroad tuner, I think 2 MPG is about what you'll gain.
If someone drives all city, all stock, then goes to an offroad tuner, I think you could easily double the MPG.

None of this is an exact science though.

 

My rig maxes out at 15mpg highway/ around 13 in town. I got a solid, hand calculated 2 mpg increase with a GBZ Tachyon 64 and a race pipe. One thing I see is that when I go from normal driving (I'm a contractor so nothing is consistent) to highway trips, the increase gains after a day or so of all-highway driving. I guess the ECM "learns" my new driving style and compensates accordingly. The reverse occurs if I've been dragging a trailer around - economy drops almost instantly and stays poor for a few days afterward.

 

You can reset the lie-o-meter, and it will calculate from the point where you reset it.
Still not 100% accurate though.

 

When dealing with "awesome" fuel mileage claims I think you generally run into a couple scenarios. One type is just flat full of crap and/or being creative, and the other has some unmentioned background info that would add to any gains claimed.

Last one I remember was some guy claiming 20 something plus MPG on the highway with his 6.4, and that was pretty much the extent of his info. After digging at him a bit it comes out he has factory gears, 35"+ tires, and a 27% Gear Vendor overdrive.

Well, duhhhh. Sure he got great mileage. On flat ground with no load. What he didn't mention, and wouldn't get, was any kind of towing capacity under those conditions.

Best I've ever gotten with mine was 16.4 with factory size tires, factory 4.30 gears, Spartan 210 tow tune, unloaded. To get that I had to stick to flat terrain, limit speed to 65 mph max, and do nothing but highway driving. It might have hit 17 if I stayed on the highway long enough and stayed in those flat terrain conditions.


Honestly I am highly skeptical of people that do nothing more than a dpf delete, add a tuner, and then claim 30% + increases in fuel economy.

I averaged 13.5 in this truck bone stock driving it back from Texas, and that was coming up rte 77 through VA and W. VA. Anyone that's drove that will know what I mean. Point is, I did the delete, the tune, cold air intake, blah blah, and my mileage didn't increase all that much.

 

It depends on driving habits, but it is very possible.

If someone buys a 6.4, uses it for all short trips and in town driving, then buys a tuner, you could expect to easily double the MPG, because stock it would be in regen CONSTANTLY.

Was that guy you speak of getting 20 MPG with the big tires and gear vendors overdrive, hand calculating it ? Just curious.

 

When I drove my truck back from North Carolina when I purchased it, it got 18 MPG, bone stock hand calculated. All winter long every tank I checked it was between 15 and 16, and that's with a little warm up in the morning before leaving for work. I have yet to check it again on a trip since it no longer regens, but if your on the freeway and reset the lie-o- meter it jumps up around 24MPG so I would guess it's around twenty on the freeway. BUT it's just a lowly 2WD, 373 gears.

 

Mine bone stock could also pull of 18 on the highway, but it sits low, and thats at 60 mph.

 

I get my best mileage after a long tow trip.

 

4x4, crew, f350, 3.73 gears, stock tires.
DPF delete, afe intake, edge race (level-2)

14-16 highway no load.
10-11 city no load.
7-8 towing 12000lb bobcat trailer (hwy)
9-10 towing 5500lb enclosed trailer (hwy)

 

I'm guessing you tow the bobcat pretty fast. The 3.73 and (I guess) SRWs should do a bit better than 7-8. I have a 4.30 and DRWs and with my Edge Racing EVO I could get around 10 depending on wind and terrain. But I rarely exceed 60 MPH which keeps me just at or a tad below 2000 RPM. I went to the H&S Mini tuner and it seems I lost a bit but I haven't done any real careful tests to make sure. Of course you're towing to make money, I'm just out on vacation trips and am in no hurry. Stock I had several legs in the 5.5 to 6.5 range. Ugh.

 

You would think. I can tow my gooseneck loaded to about the same weight as my camper and get 12.5-13.5 with it on normal terrain. That ginormous frontal area on the toy hauler (yours too) is a mileage killer, not so much the weight.

Btw, which regions you going to be bangin around this summer? So far we've been hanging out up and down the east coast but thinking this year heading out to parts west. We want to make a loop starting out across the southern states, eventually hitting the Grand Canyon area, then continue up a bit north and head back east that way.

Where did we run into you? I think it was at the KOA south of Indianapolis if I recall around July 4th weekend. Had a gaggle of Japanese women with me then as memory serves and good lord can them women eat! Feeding them cost dang near as much as feeding my truck. Wicked cute though.

 

I get 7-9 towing my 5er @ 65 mph. 13'6" or so big sail. If I were to tow a bobcat I'd imagine around 12-13 mpgs. I have the 3.73 gears.

 

Yes, there is no question dragging that big front end along costs a lot of fuel economy. yes it was Indy. We will get out of Georgia in july or august. Think it might be time to go west agaain but we haven't made a plan yet. often for the summer trips we just pick a general direction and then move as the spirit moves us. The grand canyon is great as is Flagstaff. The hard part is getting from one to the other.

 

Yes my truck is srw. I pull at 70mph all the time down the hwy. I'll pass at 70-85 too.