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Discussion Starter #1
What kind of MPG are you getting? I typically get 17.5 on the highway, with about 100-200 lbs of cargo, going 70 and using lucas fuel additive.

One of these days I'll run a tank driving by myself, no cargo, tailgate down and going 60. I want to hit 20. :thup:
 

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I get similar with Hayes DT additives, but a cap on the back CDN miles.
 

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My rig is a CC Dually with an auxiliary tank and tool box with back seat full of tools and other crap, and a 4.56 rear end. Even with all that nonsense, i get 17. Not bad for an old work horse. even before Fuel economy was a factor in buying a vehicle. Im just curious as to what im goin to get when I change overdrive from .76 to .72 and change my rear end out for a 3.73
 

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I know this might sound ridiculous, but I have no reason to lie haha. Driving with the tailgate down creates an air pocket causing drag and giving you less fuel mileage than driving with the tailgate up. I saw this on the show "mythbusters" on the discovery channel. I myself was shocked! Drive with tailgate up!
 

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My just bought -89 is getting 19.5 with 600 lbs of sand in the box for traction in 1/4 town, 3/4 highway driving. I expect to get well over 20 once the sand is gone, and with some trying. I'm considering increasing tire size a bit in the rear to lower the overall ratio. Diff is 3.55, trans ZF-5. I use ashless 2 stroke oil at 1:100 and some Power Service additive. Oh, and gate up, always. I think Hot Rod magazine did test runs years ago both ways and they got better results gate up.
 

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I get 22 tops on highway, that's going 55 on level terrain with the bed empty to 300 lbs of stuff, if I go 60 it'll drop to 20. Going slower than 55 doesn't seem to make a difference, going faster than 60 will cause the mpg to plummet. Going over mtn passes knocks off 1 or 2 mpg, still hwy. Around town is 17 at best, this can drop to 13 in winter conditions using 4x4 and long warm ups. Pulling my travel trailer the best I've recorded is 17 on level hwy, this drops to 12 when going over mtn passes. I live in Durango, Colorado so going any direction but south is gonna take you over a mtn pass. My truck has a lumber rack and 35k miles on rebuild, no fuel additives.
 

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I get 20-21 NA, CC, SRW, 300lbs tools, 3.55 gears going 65mph or so.
 

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Discussion Starter #12
I know this might sound ridiculous, but I have no reason to lie haha. Driving with the tailgate down creates an air pocket causing drag and giving you less fuel mileage than driving with the tailgate up. I saw this on the show "mythbusters" on the discovery channel. I myself was shocked! Drive with tailgate up!
Interesting! Never knew that, I'll need to do some research.

Good to know.
 

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I remember reading a thread about that years ago on the little Isuzu diesel truck forum.
Those guys are obsessed with fuel economy and they went on and on about whether is was a long bed or short bed and everything else, but in the end it didn't seem like there was much more than a 1mpg difference if anything and that's talking already in the 40mpg area anyway.:lol:
 

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I'm about 10-11 in town and 15 hwy unloaded, lose a few mpg towing some cows behind it. I've been running power service the last 6K miles so the fuel system should be pretty clean. I'm going to do the return line kit and have the fuel system checked out soon, just to be sure it's all good.
 

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15-20 mpg here but i drive 75 80 high way at 2700 rpms and up all the time
or its city stop and go crap so in all reality thats not bad
 

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91 4x4, Crew Cab, 4.10, 7.3L IDI (111,000 miles) w/ Banks Sidewinder Turbo, Banks Exhaust, Banks Transcommand, 33-12.5-16.5 aluminum wheels w/all-terrain tires. I get about 14MPG. Driving at average 62-65MPH @ 2,000RPM. How does everyone else get 16-17MPG? Do I have the fuel pump set too high?
My '98 4x4 Dodge 5.9L, 24Valve, 4.10, stock wheels/tires gets 21 MPG highway. I'm not comparing, just sharing.
 

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I average 16 mph between city and highway do speeds up to 80mph in my brick on wheels. My wind resistance is high, and I have 4.10 gears. I do have O.D via gearvendor. I just fixed my leaky return lines and did a tire swap so I will recalculate, I think I can do better not dumping fuel on the ground from the lines. I think best I can possibly get though is 18 if I drive nice with all that real estate up front. Doesn't it look aerodynamic? :lol:


 

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i got a 94 7.3 idi turbo cc dually and get 12 13
I dont doubt all of you teen and low 20 guys.. but how the heck do you get that... Im with RM in the low 12-14 range... I even turned the pump down 2 flats in hopes of not spuewing so much fuel under boost out the back... Id love to beak solid 15mpg.
 
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