at how many thousand miles did your truck seem to be "broken in" enough to get better MPG ?

i got 15.5 MPG doing 70MPH on my trip home today, at 55MPH it was reading over 17MPG.

the truck has the 3.55 gears, and had a 700 pound four-wheeler in the back, crew cab fully loaded with me / girlfriend / camping gear.

my truck currently has 1400 miles on it.

could i hope for better MPG in a couple thousand more miles ?

Edit- i know 15.5MPH at 70MPH is pretty good for 10,000 pounds or more of vehicle, but id love to see 17MPG at 70 miles per hour like my 2006 6.0 got. ( then the 2006 for 18.5MPG with the chip )

 

mine have been getting slowly but steadily better... it seems to depend a LOT on where I buy fuel. I'm getting close to 2k miles and at 65 (on "good" fuel) I'm getting about 18.5. One week from today I'm setting out on a 2300-mile round trip that should complete the break in

 

I agree with the variations in fuel, I might start using an additive.

I have just over 10K on mine but I have not driven unloaded in a long time. I get 12 at 72mph pulling a 16ft trailer.

 

+1 on the additive

that's what I've been thinking too, especially since I'm about to be on the road for a week and have no idea if each stop's fuel is any better than the last. actually... I will start a new thread on this. sorry to hijack

 

I know with older diesels people often reported the best mileage starting around 40K-50K miles on the clock. I suspect that your trucks aren't anywhere near to be broken in yet.

 

Mine just turned 10500 miles on last weekends camping trip. Between the new computer programming and more miles, the truck just keeps getting better. We went a total of 365 miles and avg mileage loaded was 13.5. Nice tailwind for the return run. I would also agree that some tanks of fuel do better than others.

Regards

 

I have a 2011 F-350 Dually 6.7L with just over 5,000 miles and been constantly getting 16mpg pulling and 19mpg solo at 65. 5 mpg's better then previous. At first it was only getting 14mpg.

 

I just got back from Mrytle Beach S.C pulling 11,000 lb. fithe wheel. Trip miles 584 and at 65 mph averaged 9.5 mpg.

 

In city driving, my truck actually seems to do better when I don't feather the peddle so much. I do a lot of city driving (stoplights every 1/2 mile) and if I baby that peddle like there's a rotten egg under it, I get 11.7. However, the day I figured out it could do better was the day I got tired of going so easy on such a powerful truck. I flicked off the MPG average indicator on the display so it wouldn't sit there and remind me what a bad driver I was and just started driving it normally and now I get a full mpg better than I did before (12.8).

By the way, I'm up to nearly 3K.
Now... I'm sure this will draw quite a bit of speculation but... 'bout a month ago, before the flash update, I wanted to see what I could get on the highway and so reset the average mpg's after I got up to speed and feathered that pedal like you wouldn't believe it. I then drove on the interstate up and down overpasses/underpasses and up and down some small hills for 20 miles to my destination. At that point, I was getting 34mpg. My errand was right off the freeway. I then turned around, accelerated back up the onramp and retraced the exact same route back to exactly where I had started. My final average was 28mpg over a distance of 40 short miles at speeds in traffic, ranging from 50mph to 65mph. As soon as I resumed my stoplight to stoplight city driving, that average dropped like a rock, understandably so.

 

Huh....I got 9 with my 05 V10 pulling a 11000 pound fiver....I hope you get better than that later on.

 

Seemed like my 7.3L engines used to get better at 10,000, then another increase about 50,000. On my 6.0 though didn't see like it ever changed.

 

We went looking at the leaves here in northern Vermont with a lot of up and down hills, next day went to Burlington and back a total of about 350 miles and averaged 18.1 mpg.The truck has 800 miles on it with 3.55 gears with 295/65/20 tires on it. We are going out of state this weekend and it will be all highway for 250 miles each way. We'll see how it does?