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Discussion Starter #1
Just wondering why the new trucks with more power and more emissions seem to be more fuel efficient than the good ole 5.9?

I have a 2006 with slightly over sized tires (about 32" BFG AT KO's), drive the speed limt and the best I have ever gotten is about 18/19mpg on the highway.

THanks.
 

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Rear Admiral Rickard Onmi
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transmission, tuning, gearing.

4 speed vs 6 speed with a double overdrive

while they do have more power, it's rarely used. tuning prevents heavy use of the power most of the time and most of the power just isn't needed 90% of the time. The tuning is optimized for fuel economy

3.42 gears on alot of the newer trucks, i think the 19s are getting 3.73s again. meanwhile 3rd gens usually have 4.10s and 3.73s IIRC
 

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Rear Admiral Rickard Onmi
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My 05 gets 16-22. Less if I’m pulling the horse or camp trailers.
you mean to tell me with the added horse power in the trailer you don't get more?
 

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These old trucks can get just as good or better fuel mileage then the new ones....
 
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My 04.5 is averaging 17.5 unloaded mixed driving and I averaged 14.5 mpg towing about 7000 lbs all highway for 1700 miles recently. All hand calculated figures. Freshly rebuilt engine, new clutch and new injectors right before this mileage calculation took place.

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My last tank was just under 16mpg hand jammed. That’s unloaded mixed highway/city with 37s, 100% over injectors, and a jackass behind the wheel. Oh and I have a few fairly significant fuel leaks I’m in the process of fixing. I think with a little more maintenance (previous owner did absolutely zero it seems) I can get close to 19 or 20.
 

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TECH SPECIALIST
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TECH SPECIALIST
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So I got motivated to have a look at all my receipts that I have on hand (some are stashed in a pile somewhere) and for the last 20425 miles, averaged 21.137 mpg. I can see in the data where things turned south with a wrong turn in the tuning. Since fixing it I have 1 tank done, one that took me on a pot holed dirt road up to a trailhead, an hour in & 50ish minutes out plus 2200' elevation gain. that was 21.5 tank and included minimal eco driving (maybe 1/4 of the fuel used). In that data were several road trips that had DGAS tanks included in them. Lots of 75~85 mph speeds over long stretches. During that time frame, the front 2nd air dam I made was not installed, I believe that mod is good for ~1 mpg at higher speeds. Last year, similar trip on the same roads, driving the same way, I managed 19's, this past year was 17~18's. It did however also have a different tune and the rear bumper mod was missing this year whereas it was present last year.

anyways...
 

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Also the newer trucks run higher rail pressures, and more advanced injectors. The newer injectors can fire more times per stroke than the older ones for a more efficient burn.

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To OP. I don't know any newer trucks that get better mileage than I get. That doesn't mean they can't or don't, the peeps I know who have them arnt even close. I read the thread Steve posted and its quite impressive. As of right now, I can do over 800 plus miles per tank at 55mph easy. Keys to this,
Tire pressure I. E. Max the fronts, at least 65min. Rear.
Weight, with my 2wd, qc sb, with weight removed, I'm at 5950lbs. with a 1/4 tank of fuel.
Speed, anything over 60mph is killing you.
From a stop, never go over 6/8 pounds of boost, ever.
Tuning, fo sho, it truly does help tons, I just have a old smarty jr set on kill( max on all settings except torque management). Just abideing by those will help your mileage YUGE. From there, its the devil in the details like Steve has done exceptionally well.
 

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Weight, with my 2wd, qc sb, with weight removed, I'm at 5950lbs. with a 1/4 tank of fuel.
Speed, anything over 60mph is killing you.
No wonder you guys get such good fuel economy, my truck is 5360 on the rear axle and 5120 on the front . I run 80-85 when on the hwy and can squeeze 13 out of mine
 

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No wonder you guys get such good fuel economy, my truck is 5360 on the rear axle and 5120 on the front . I run 80-85 when on the hwy and can squeeze 13 out of mine
you sir need that 2nd front air dam... i suspect, no proof though, that it is good for 1 mpg at high speeds... $30-35 in parts @home depot...
 

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I put a Laramie bumper cover which is around 1-1/2” lower than the factory bumper and rigged the factory air dam to it mainly for looks but hoped it would help also . Got 35” mud tires which don’t help either .
 
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