optimal highway speed
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optimal highway speed
hey guys, every time i take a trip i spend about half the time trying to find the best highway speed for mileage. So far it seems the best speed is about 62 mph at 17 to 18 mpg. My truck is jacked up tho and im the 6.0 diesel
My buddys dodge he gets the best mileage doing about 85....i hate going so slow
My buddys dodge he gets the best mileage doing about 85....i hate going so slow
Last edited by johnf350diesel; Nov 17, 2008 at 12:31 PM. Reason: added engine
Senior User
Joined: Aug 2008
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From: CA
Yup, keeping revs below 2k is the key. My current gasser has 4.30 rear end so 65mph yields the best mileage but when the highways wide open 75mph seems much more natural but mpg will suffer.
If all you want is mpg then I'd recommend 55mph along with the big rigs. The engine won't be spinning too slow to worry top gear but it'll certainly be going slow enough to help mileage big time. Just allow extra time.
If all you want is mpg then I'd recommend 55mph along with the big rigs. The engine won't be spinning too slow to worry top gear but it'll certainly be going slow enough to help mileage big time. Just allow extra time.
Postmaster
Joined: Mar 2001
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From: So Cal
All depends on your truck, equipment, traffic, driving style etc.
My 94 F250 longbed supercab 4x4 460 4.10 E4OD gets very different mileage depending on freeway speed.
Below about 60mph, it almost doesn't matter how I drive, gentle versus enthusiastic but not crazy. But above 60 there is a big difference in mileage.
For years I lived in Oregon where driving 60mph in my truck was easy to do and I got about 10-11+mpg. Here in So Calif, if I go less than 80 sometimes, I will get run over by little old ladies, my truck is hard pressed to average 10mpg. So only difference I see is freeway speed and maybe air temps.
Our trucks are not sleek aerodynamic vehicles so it makes sense that at higher speeds our brick like qualities come out and drop our mileage.
Just my experience,
Jim Henderson
My 94 F250 longbed supercab 4x4 460 4.10 E4OD gets very different mileage depending on freeway speed.
Below about 60mph, it almost doesn't matter how I drive, gentle versus enthusiastic but not crazy. But above 60 there is a big difference in mileage.
For years I lived in Oregon where driving 60mph in my truck was easy to do and I got about 10-11+mpg. Here in So Calif, if I go less than 80 sometimes, I will get run over by little old ladies, my truck is hard pressed to average 10mpg. So only difference I see is freeway speed and maybe air temps.
Our trucks are not sleek aerodynamic vehicles so it makes sense that at higher speeds our brick like qualities come out and drop our mileage.
Just my experience,
Jim Henderson
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From: Spring Lake
If you can get your truck on a dyno get your hands on the graph. Pay special attention to RPM vs hp and torque. Since what you are looking at is a function of energy (power) you want to find a balance of torque and horsepower. The less horsepower, but good torque will be your optimal cruising RPM.
I'll try to get a dyno graph to draw up what I'm trying to explain. It's not an exact thing but it will give you insight.
I'll try to get a dyno graph to draw up what I'm trying to explain. It's not an exact thing but it will give you insight.
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Joined: Oct 2005
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From: SW Virginia
hey guys, every time i take a trip i spend about half the time trying to find the best highway speed for mileage. So far it seems the best speed is about 62 mph at 17 to 18 mpg. My truck is jacked up tho and im the 6.0 diesel
My buddys dodge he gets the best mileage doing about 85....i hate going so slow
My buddys dodge he gets the best mileage doing about 85....i hate going so slow
Setting the cruise at 72MPH in my 2005 6.0 gets me around 18. Best I ever did was 20.3 on 55 MPH road in NC (hand-calculated). Truck was about 6 months old at the time with about 5000 miles on it. Haven't been there in a while (55MPH that is) but it would probably be better now at 30,000 + on the clock since it's a little more broken in.
Hotshot
Joined: Dec 2006
Posts: 14,069
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From: Melbourne, Ky
Mileage will vary from truck to truck. My work truck, 97 Super Duty, runs 2600rpms at 70 mph. Best fuel mileage is obtained at 55 to 60mph. My 02, F250 Crew cab, gets 18 at 70mph, but would do better if I kept it close to 60. I choose not to. My brothers work truck gets around 10mpgs at 70mph, but he can't use high gear. In high gear, at 70mph, he's at 1600rpms,1700rpms gets him up to 78mph. Best mileage is achieced for him at 1900 to 2000rpms. His truck is a 1994 Volvo/GMC/White with a 13 speed and a 3176 cat engine. Weighs less than 24,000lbs. Talk about an identity crisis, his truck has 3 names on it!
Even though his truck weighs twice what mine does, I only beat him by 2 to 3 mpgs at best.
Even though his truck weighs twice what mine does, I only beat him by 2 to 3 mpgs at best.
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in my 99 7.3 i drive rpms for the best mileage1800-2100 are the best numbers for me during long sustained driving. i know the 6.0 has another gear so it runs a little lower rpms in the highest gear. try taking off about 1/4 to 1/2 throttle and see were the trans shifts at. mine shifts a little lower than 2000 and my sweet spot is around 2000
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Joe Kucinski
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Joined: Jul 2002
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From: Long Island USA
Usually below 2K RPMs is best, both for diesels and the V10 gasser - not sure about the 5.4
Funny, with 3.73 gears on my V10, I get better mileage at 70-75MPH than 60-65MPH. A few years back, a bunch of us were all reporting the same thing.
Funny, with 3.73 gears on my V10, I get better mileage at 70-75MPH than 60-65MPH. A few years back, a bunch of us were all reporting the same thing.
Lead Driver
Joined: Dec 2006
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From: San Diego, CA
1600rpm is my max torque and would be the ideal cruise control setting, but that's around 55mph. I've hit a happy medium at 1800rpm which is just under 65mph. Depending on wind and hills I can get anywhere from 17-20mpg on the highway.
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Less ruppums=better mileage. Go as slow as you can in top gear, and you're there...eventually. There is no way any truck gets better mileage at increased speed; none, nada, zip. That notion goes in the category of rationalizing stuff- so your wife let's you do it!
(Think of drag coefficient and how that works as a square of the frontal area and speed)
(Think of drag coefficient and how that works as a square of the frontal area and speed)
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Joined: Jul 2002
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From: Long Island USA
But that's the V10, which has a peculiar dip in the torque curve right where my truck runs at 60-65MPH.
Anyway...
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wow i didnt expect such a wide variety of answers. and no, i'm not expecting great mileage...in fact im fine with what i am getting...I just wanted to see what everyone had to say. I get better mileage with my jacked up truck than i did in a explorer. under 2k rpm is definate.
