75 MPH mileage

[BerylPugh]

I can't understand how people get over 18 MPG @75 MPH with these trucks. 04. 5 4x4 3. 73 6-spd LWB. I can't get these numbers @65 with the cruise on. How big of a deal would a high flow air filter and muffler (donaldson or similar) be on this truck. Pulling power seems to be there but the fuel economy isn't. Pull a 6000lb (empty) 21' desert fox toyhauler that is very tall (11-12 ft) and @75 my overhead says 8. 2-9. 2 My underpowered ford V-10 didn't do much worse than this.

 

[bmoeller]

Did you check the mileage by hand also? The display only gives you an average from what I've read here. Empty with my '97, I have gotten 16+mpg running 70-75 w/4. 10s and stock size tires.



Remove or gut the cat. That should help too. The more the truck gets broken in, the mileage should go up over time.

 

[mbaston]

At 55 I have gotten as high as 21. 5 empty. 65 gets me about 18 or 19. 75 gets me 16-17. This is on level ground, no wind and #2 fuel. Hauling, I get around 10 with a travel trailer and about 12 on the last 5th wheeler I pulled.

 

[GFritsch]

BP, Don't believe everything that you read. --not directed at anyone in particular.

 

[DKiesewetter]

I just got back from OKC... on the return trip i set my cruise at 65 and slowed a little on uphills... I got 19. 7 hand calculated... that's not too bad. Highest previous milage was 17. 95 hand calculated. I have repeatedly hadf tanks around 16 MPG... all in town driving gets me about 12. 6-14. 2 MPG.



Doug

 

[JLehman]

Hi, I got some bad numbers for awhile, now with 3700 miles on it its startin to climb. This with a Ca SO truck. 14. 5-- 16 town, 15. 5 --17. 3 at 70 to 80mph freeway. started at about 13, was real dissapointed as u might imagine. Finally its gettin better and all posts seems to confirm more to come. fingers crossed, i'm hopin.

 

[Gypsyman]

Lots of variables! I use my personal truck for work and get about the same at 75 mph. Check my sig for truck type. By watching my pyro and boost in different given driving conditions, it doesn't take alot of wind, speed, grade or weight to drop my mileage alot! Empty @ 75 I see anywhere from 13. 2 to 16. 8 mpg. Throw my 11' tall 6800 lb empty gooseneck behind it and try to go 75 mph and you get 7. 9 to 9. 2 depending on wind direction. I know this for a fact as I just picked it up at the factory and drove 1645 miles straight thru back home. Freaked out when I saw my overhead AND hand calculated mileage at every fillup. Then I remembered that my Big Block Chebbie only gets 4. 1 to 5. 3 with a like amount of weight behind it and sure as HE$$ won't do 75 mph up a 6% grade!

 

[Gypsyman]

Originally posted by BerylPugh

I can't understand how people get over 18 MPG @75 MPH with these trucks. 04. 5 4x4 3. 73 6-spd LWB. I can't get these numbers @65 with the cruise on. How big of a deal would a high flow air filter and muffler (donaldson or similar) be on this truck. Pulling power seems to be there but the fuel economy isn't. Pull a 6000lb (empty) 21' desert fox toyhauler that is very tall (11-12 ft) and @75 my overhead says 8. 2-9. 2 My underpowered ford V-10 didn't do much worse than this.

IMHO the only thing the exhaust and drilled airbox did for my truck was make my mileage go down due to the fact that it sounds sooooooo good now I can't keep my foot out of it!!!



Seriously, I saw no change in mileage up or down, just dropped 50* to 75* on my EGT's.

 

[DIESELMAN]

Beryl - Now that I've had mine for a year and a half, I'm sure my driving is consistent, I get 19. 2MPG empty and I burn 100 gallons between refueling so I know its a good average and when I pull my 32' Desert Fox (28 Foot Box) which is also 11' tall, I get 11 - 14 MPG at 65 and 10 MPG at 75. I pulled to Alaska at max Gross last year and averaged 13. 4MPG over 3800 miles.



My V10 2500 was lucky to get 6mpg pulling an 8000 pound trailer with my boat on top of the truck, but it would do 80 with ease.



I never Idle my rig except to cooldown and only hotrod when people are looking

 

[BerylPugh]

mileage

DIESELMAN

These are some really good numbersconsidering max weight. I believe the poor mileage I get can be blamed on the barn door aerodynamics of the desert fox. When I would pull with V10 it didn't matter whether it was empty or full always got pretty much the same. 100 gal of water/2 4x4 quads/ 2weeks of hunting stuff gets really heavy. Although I can pull most grades in 6th with this truck (had to downshift to 3rd/4000-4500 RPM with V10) Couldn't even use OD (5-spd manual) on the ford unless I was going downhill. I don't think I would ever have to shift lower than 5th with the diesel no matter how steep the grade gets.

 

[doldenburg]

yea- and i get 30 mpg at 80 mph pullin my 40 footer

 

[loncray]

I usually drive on the highway around 75 mph, and I'm getting 18. 5 - 19 every time I do it. That's with a tall cap, towing nothing, bed with a few hundred pounds in it, and two passengers. Oh, and a lead foot - which is why I'm getting 15. 5 - 16. 5 in stop and go traffic.

 

[JRMora]

Originally posted by BerylPugh

I can't understand how people get over 18 MPG @75 MPH with these trucks. 04. 5 4x4 3. 73 6-spd LWB. I can't get these numbers @65 with the cruise on. How big of a deal would a high flow air filter and muffler (donaldson or similar) be on this truck. Pulling power seems to be there but the fuel economy isn't. Pull a 6000lb (empty) 21' desert fox toyhauler that is very tall (11-12 ft) and @75 my overhead says 8. 2-9. 2 My underpowered ford V-10 didn't do much worse than this.

I seen some big numbers, too, but here's what I get:



'04 HO (305/555), 6 speed, 3. 73, DRW, 4x4, driving 75-80 (relatively flat ~ 50 miles each direction) I'm getting 17. 3-17. 5 on the overhead, 16. 5-16. 8 hand calculated. Over the last 2,000 miles or so I saw my mileage drop about 1-1. 5 mpg. Changed my fuel and air filters and I am back to 17. 3.



I have about 15000 miles on my truck



If I drive 65, I see about 1. 5 mpg more.



My truck is bone stock except for guages.



I saw 18 (hand calculated & corrected) over the same conditions with my '97 (5 spd, 4x4, cap, 3. 54's, and 265 BFG's. )



Juan

 

[BerylPugh]

Loncray

I notice you have a tall shell. Do you think it hurts or helps your mileage? I have the very high LEER and it doesn't seem to do either. I think it helps when towing a tall trailer because it cuts down on the surface area of the trailer being exposed.

 

[Mathew Clausen]

No one will get 18mpg pulling a 12' tall 6000lb trailer at 75mph! You should get around that empty, level, with no headwind.



Also - keep in mind that as you get down in the range of 8-9 mpg - a 1mpg decrease is a large percent change. When you say the ford V10 didn't do much worse, how much? If it got 7 ILO 9, that is a 28% increase for the diesel. Pushing a lot of air at a high speed takes power (which takes fuel) - no way around it. A diesel has biggest gains over gas engines at light loads (no throttle losses) - when you get to heavy loads you lose some of that advantage as the gas is nearly wide open anyway. 20-30% is about all you can hope for. There are no miracles.



Mathew

 

[Gypsyman]

Well put, common sense.

 

[Crunch]

Originally posted by BerylPugh

I can't understand how people get over 18 MPG @75 MPH with these trucks. 04. 5 4x4 3. 73 6-spd LWB.

I can get just over 18MPG at 75MPH from about March to December. After that I noticed a winter drop to about 17MPG at 75MPG. If you look at the truck configs in the signatures I think you'll find that the people who aren't getting 18MPG have 4X4s. I've seen as high as 20. 78MPG over a tank and highway cruising empty at 75MPH. That transfer case is still turning, even if it ain't turning the front wheels and that costs you in fuel economy.



Edit: I have the 3. 73 gear ration in the rear end. I bet most of the high mileage figures come from fellow 3. 73ers.

 

[Gypsyman]

I agree. The lower mileage figures almost always seem to come from 4x4's. Higher front profile, more weight, more mechanical drag, ect.

 

[DPKetchum]

Wish more folks posting would show their gear ratio etc. Anyhow at 70/75 mph about 15. At 65 mph about 16. 5 or so.

 

[SSage]

My Turn

03 dually 4x4 HO Auto QC 4. 10 LS 10K + miles, changed the fuel filter at 9K.



Solo I get 12. 8 mpg average. Atlanta metro traffic all two lane. Highway (70 mph using the cruise control) I get 14. 0 to 14. 8 mpg with three aboard and 500 to 600 pounds in the bed. Totally empty on flat highway at 65 mph I saw 18 mpg once when new. Haven't seen it since, but I've added some weight to the truck in the form of an in bed 50 gallon tank and tool box, plus hitches, chains, 100 lbs of tools and such.



I pull a 24 foot deck over axle trailer that weighs a good 4500 empty. Loaded or empty I've been staying close to the same 11 or so mpg at 75 mph on open highway with rolling hills. For some reason my over head computer works well, on a trip from GA to TX, I got 14. 8 from the truck and 15. 0 on paper based off what I was putting in the 50 gallon bed tank. I only figure on the aux. tank. I can fill it exactly the same amount each time and I try to use the same pump, almost always get the same pump.



I've learned to slow down, 60 to 65 towing. I've picked up close to 3 mpg since new. I got about 10 mpg when I started towing with it. I can do 12. 8 with out too much trouble (65 max) pulling the same loads. Not bad, my gas trucks got well under 10 mpg and could only do 50 mph on the two lane hills loaded. Now, I have the power to run the same hills at 70 mph. Mucho fun, produces about 11. 1 at 70 with the trailer empty and at least three passes per trip.