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2017 F250 Superduty poor MPG

Bought a new 2017 ford F250 super duty 6.7 L diesel this year. Started out with great fuel mileage 19.5 to 20.8 on the highway. Did the first oil change at 3000 miles because we had a long trip ahead of us. During the trip which went from Texas to Canada and back to Texas we crossed the 7000 mile mark on the odometer. The fuel mileage is now 15.3 on the highway at best. We picked up fuel in Wisconsin Illinois in Oklahoma at truck stops. Can anyone explain the sudden loss in miles per gallon and could it be associated with the fuel? We have only used the standard diesel fuel no farm diesel or lower grades. We reset the fuel mileage several times and it stays about 15.3 on the highway. We also added 2.5 gallons of DEF in Canada. Any help or suggestions is appreciated. We have the truck under the extended seven year bumper-to-bumper warranty so it can go back to the dealership if something is wrong.
 

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there's nothing wrong with it. 15 is great for a v8. You should not expect anything more from it. I hear ......i get 20 mpg in my V8 diesel........and higher from some . Pipe dream...... not going to happen in a V8 diesel. I've owned them since 99 and have never ever ever ever beat 15-16 mpg on hwy with 3.73 . 4.10 a little lower. Drive it and enjoy

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there's nothing wrong with it. 15 is great for a v8. You should not expect anything more from it. I hear ......i get 20 mpg in my V8 diesel........and higher from some . Pipe dream...... not going to happen in a V8 diesel. I've owned them since 99 and have never ever ever ever beat 15-16 mpg on hwy with 3.73 . 4.10 a little lower. Drive it and enjoy

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I would have agreed with you before I got my 2017. I am hand calculating and getting 18 to 20 mpg with speeds of 70 to 80 mph. I have, as signature shows, owned many diesels. Also most have 3.55 gears. Fuel brands do matter. I have 8k miles on truck.
 

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Had to add this,

my 02 F350 CCLB 7.3 tuned and done right with all the goodies. 6spd. 3.55
4x4
6 inch lift.
36" Dura Tracs

Travel with it all the time on the highway . Hand calculated 25 mpg !

My 08 similar, 15............. Too much junk on the newer engines...........
 

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Discussion Starter #5
I would have agreed with you before I got my 2017. I am hand calculating and getting 18 to 20 mpg with speeds of 70 to 80 mph. I have, as signature shows, owned many diesels. Also most have 3.55 gears. Fuel brands do matter. I have 8k miles on truck.[/QUOTE]

Once we got back in Texas and had different fuel, the MPG went back up to 18 and 19. We also hand figured our entire 4800 mile trip and averaged 18.6 MPG. This 2017 is a great beast! So far I think FORD got it right. I believe our problems were the fuel andat times we have the cruise control set at 78-85, especially on I-30 in TX
 

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I would have agreed with you before I got my 2017. I am hand calculating and getting 18 to 20 mpg with speeds of 70 to 80 mph. I have, as signature shows, owned many diesels. Also most have 3.55 gears. Fuel brands do matter. I have 8k miles on truck.
No disrespect...... But I'm having a hard time with that. I haven't hand checked mine yet but then again I'm running 4.10

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I'm wondering it you got some leftover winter diesel while in the northern states or Canada. It should have been long used up as most of the stations switch over around April but that's the only explanation I can come up with. That stuff costs me a couple MPG every winter.
 

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No disrespect...... But I'm having a hard time with that. I haven't hand checked mine yet but then again I'm running 4.10

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4.10's make a big difference as does how you drive and city versus highway. I have no trouble believing 18-20.

I have only calculated accurately one truck's mileage. It was my 99.5 when I bought it new in 99. I entered every fuel receipt into a computer program. I sold the truck 3 years later with 303,000 KM on it and I got 15.5 MPG Canadian, that's about 13 US for the life of the truck and that was with at least 40% of the miles towing 4K-8K. It was a 172" wheelbase 4x4 with a 70 gal bed tank so it was heavy all the time.

When I start hearing 20-25, I start to struggle with believing it. There has to be a very special set of circumstances. "I lived at the top of a mountain and drove down to town everyday but had the truck towed home"
 

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My 2017 F450 with 4.30 rear end is getting about 16.5 mpg unloaded, strictly highway, mostly flat, mostly 55mph with some 65 mph thrown in. I'm pretty gentle on acceleration and use cruise control 95% of the time.

When loaded with an almost 5700 pound camper (yes, I know that is over the rated payload) and driving 60mph it gets about 10.5mpg in the mountains and 11.5mpg on fairly flat terrain.
 

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No disrespect...... But I'm having a hard time with that. I haven't hand checked mine yet but then again I'm running 4.10

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No disrespect taken, just wanted to let forum know where I stand. You seem to be in the minority with you opinion and your 4.10's and a major problem for highway MPG.0:)
 

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No disrespect taken, just wanted to let forum know where I stand. You seem to be in the minority with you opinion and your 4.10's and a major problem for highway MPG.0:)
I'll get a hard check on it with more miles and I'll see where I'm at.

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I've been 15-17 in mine, but that includes a lot of local driving and stop and go on Houston's parking lots...err freeways. Heading on a 1800 mile round trip roadie in a couple of weeks, curious to see where I land on a long haul at 75 on cruise control.
 

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there's nothing wrong with it. 15 is great for a v8. You should not expect anything more from it. I hear ......i get 20 mpg in my V8 diesel........and higher from some . Pipe dream...... not going to happen in a V8 diesel. I've owned them since 99 and have never ever ever ever beat 15-16 mpg on hwy with 3.73 . 4.10 a little lower. Drive it and enjoy
Not true. Before the switch to ULSD in 2007, my 7.3L Powerstroke regularly got 20-21mpg on the highway and even once got consecutive tanks to hit 22.5mpg on a long trip. Truck was and is still totally stock.

Since ULSD, the best I can squeeze out of the truck is 19mpg hwy, but mixed driving usually puts around 14-15mpg.
 

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I've had my 2017 F350 Lariat for a week, I have 1500kms on it and it says average 15.3L 100/KM. Too new, way too soon to think about it. And yes I'm Canadian so I have no idea what MPGs would be haha.
 

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I've had my 2017 F350 Lariat for a week, I have 1500kms on it and it says average 15.3L 100/KM. Too new, way too soon to think about it. And yes I'm Canadian so I have no idea what MPGs would be haha.
Google says 15.7 MPG
 

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I've been 15-17 in mine, but that includes a lot of local driving and stop and go on Houston's parking lots...err freeways. Heading on a 1800 mile round trip roadie in a couple of weeks, curious to see where I land on a long haul at 75 on cruise control.
I drive in Houston's stop and go freeways, 84 miles round trip to work everyday. to an from work I get I get 17.3 to 18.1 and what I head to my lease I can hit 19 I have 7500 miles on it. Now i have had times just around the house quick trips here and there I do drop around 15. I do run opti-lube and arck oil not sure if they help. have gotten good mpf from day 1.
 

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Im all for better mileage, but 80mph and 20mpg is bull****.

Ill pay for the gas, and if you can get almost 1000 miles (960 on the 48gal tank and 680 on the 34 gal) before needing fuel again at 80 mph, Ill buy you two more tanks. :)

Im in Houston. Headed to El Paso next weekend, you can tag along. :)
 

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Im all for better mileage, but 80mph and 20mpg is bull****.

Ill pay for the gas, and if you can get almost 1000 miles (960 on the 48gal tank and 680 on the 34 gal) before needing fuel again at 80 mph, Ill buy you two more tanks. :)

Im in Houston. Headed to El Paso next weekend, you can tag along. :)
I have to agree, I drive 80 a lot and I notice that after 65 MPG tanks pretty quick. I drive between 60 and 80 mph on my work commute 84 miles round trip and see around hight 16's to 17.1, 18 if I keep foot out of pedal. Open road long stretch I have hit 19 and that is speeds 70 to 80. I have not done a hand calculation yet but have not seen anything over 589 miles for a tank I have a 34 gal.
 

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I think some people expectations are a bit high. These are work trucks. I'm actually impressed that the fuel mileage is as good as it is in most cases. There are full size luxury cars with fuel mileage not much better. I'm a firm believer that fuel economy depends mostly on driving habits. Of course there are other factors such as quality of fuel, altitude, topography and traffic amount others. I've found that 55 to 60 MPH is a good speed to get reasonable fuel economy but an awfully lot of folks seem to always be in a hurry.

My 2017 Super Duty Platinum FX4 gets around 17.3 MPG at 70 MPH and about 18.4 at 58 to 60 MPH.
 

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there's nothing wrong with it. 15 is great for a v8. You should not expect anything more from it. I hear ......i get 20 mpg in my V8 diesel........and higher from some . Pipe dream...... not going to happen in a V8 diesel. I've owned them since 99 and have never ever ever ever beat 15-16 mpg on hwy with 3.73 . 4.10 a little lower. Drive it and enjoy
My '03 7.3L Powerstroke regularly got 20-21 on the highway before ULSD. Since the switch, the best it has done is about 18-19 tops (and the 19 may be generous).

On a long trip to PA and back, I got consecutive tanks of 22.5 and that's no joke.
 
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