I 10 in Texas rolls legal at 80 mph. I head into San Antonio and roll at about 85 and the further out I am the faster I can roll so it peg 90 and the state boys give you 10 so as long as the weather is good they let you fly.

After almost 8000 mi and 10 mo of ownership I have noticed REPEATEDLY that mpg goes up the faster I go (up to about 90). I just came off a 247 mi trip and on Trip 'B' my mpg was 9.1 when I rolled into the barn.

Today I head out, jump on I 10, traffic is very light and it rolling hard 85-90, dry and blue skies and I wave at the Sheriffs car as I roll into town. I pull off I 10 at the COSTCO for resupply, park and check my mpg...9.6.

Fluke? NOT hardly, I have been noticing this for the last 10 months.

my '11 peaked mpg at 62-65 and it trickled down as mph increased.

My '15 is just the opposite.

Both the '11 & '15 were equipped the same: DWR, 3.73 gears, all OEM except shocks (Ranchos).

I travel a lot for business, leaving out on Thur/Fri rtn Sun/Mon, use the Trip 'B' to get mileage for tax purposes, been noticing the increase when I get back.

NOTE: Sometimes I have my camper on the back of the truck and YES I will also see a increase in mpg when I increase my speed from the 62-65. I only drive faster than that on open Interstate, light taffice and good weather. The truck has no issue as all rolling at 80 mph with my 6000 lb camper in the bed of the truck and mpg will incrase by about .5 + mpg...

Anyone else noticed this phenomena?

 

Sounds to me like you've mastered physics and/or created a worm hole allowing you to blaze thru it without any friction.

 

My first inclination would be some kind of change in the movement of air around the truck as speed increases. If could be that at higher speeds the air pocket created by the front end/air dam makes a bigger envelope or vortex that allows the truck to slip through better.

It could be a larger turbo too. Might be more efficient at work than the '11.

Half a MPG over a week of driving isn't a lot though. It could be barometric pressure, humidity, fuel quality, clean paint, or the tires (as they wear they roll better and get smaller around by almost 1/2".)

 

So where does 800 Torque come into the picture?

 

From how I've heard the turbo described, it's got to be that.

 

We are talking boosting Avg MPG as depected on Trip meter 'B'. So I leave the barn where the truck is parked and Avg mpg will rise .5+ by the time i make it down I 10 to the COSTCO, about 35 mi.

To say this has caused me to think about it would be an understatement so here is my theory:

Ford gives us 800 lb of torque in that engine, but unlike my days where we played with cam profiles to move the torque curve around Ford does that for sure, but they manage it thru the magic of electrons (the computer).

One of the things I have noticed the the BRUTAL acceleration at highway speeds beyond about 60 mph. In fact the 60>100 will nail you back in the chair and make telephone poles look like a picket fence. My '11 would never do that, I had a LOT more on the bottom and mid range and by the time it got to 80 he had left most of its torque behind it.

My Z06 corvette regularly handed me 23.x mpg cross country with an avg speed of 83 mph running at night with my Valentine 1 set for max boggie. Drop down to 55-65 mph and I was seeing 27-28 mpg. This is not unusual in hi-perf cars with serious HP/T.

An incredible powerful engine that in 6th gear at 80 mph its not breaking a sweat, same same this beat of a diesel we drive and my guess Ford has chosen to unleash the beast in the upper part of the rpm band. Then engine clearly does not work as hard at 80 as it does at 62 relative to where in the rpm band its getting the most juice.

I have said all along I should have got the 4.10 gearset over the 3.73 as I think it would provide and overall boost in mpg by putting the engine deeper into the torque curve.

By the way I have not been able to find a torque curve for this engine '(15), anyone know of a Factory OEM as publish by Ford on this years engine?????

 

Very interesting.

Have your MPG readout values been matching hand calculations at the pump? Years ago I was a professional truck driver, and in my experience fuel economy goes down much faster driving a large vehicle at speed than a smaller one. I don't see how it's possible for efficiency to increase with speed, but perhaps the accuracy of the MPG readout varies with RPM?

 

Tom, no I have done hand cals. What I have seen over the past 10 mo of consistent increase in mpg as my speed increases above 62 mph loaded or unloaded.

On one trip I got way behind the curve in doing some sightseeing and suddenly found myself having to drive long and hard to make up the time. I was loaded and typically set cruise at 62 mph on I-state. So to compensate I moved my cruise setting up to 78 and drove most of the day until I arrived on time for my meeting. It was a bit over a 300+ mi day all on I-state. I picked up over 1 mpg increase. While I had noticed this in the past it was always on a short run and I just wrote it off to less traffic, tailwind or whatever and it was only a few tenths anyhow. So have have playing with it, and watching it closely and yes it does in fact show a consistent increase in mpg at my avg speed increases above 62 all the way up to about 78 mph loaded and 80 mph unloaded.

My premise is that the engine is dumbed down by Ford to save the driveline and you do not get access to the big torque numbers until you get past some point in the rpm band.

You can look up city/hwy numbers and the gap between for hi-perf cars is amazing. In the old days, my '69 427/435 hp corvette got 12-15 in town and about 14-16 on the hwy, todays modern hi-perf engines can deliver mid teens in town and high 20's on the hwy.

The BIG punch in my '15 6.7 is on the hwy. It has good low end albeit is traction limited, but its mid range is weak compared to the available performance at hwy speeds.

 

Both my 2011 and 2016 like to be driven at 120km per hour or more. I do get better mileage at the higher speeds because its hilly here and I think I can coast up a hill easier if more momentum is applied before hand . I know Texas is not hilly though for the most part.

 

LOL:
31,000 square miles of Texas Hill country, I live on a hill at 1820 ft; it ranges from about 900 ft to 2500 ft in elevation and its hill after hill after hill etc. It will eat your mpg alive.

 

are ant hills are taller than that in Alberta lol. Just ribbing you, we are pretty much in the mountains here.

 

I bet you guys do up in that neck of the woods, we have a mountain, maybe two out in SW Texas but not many....

 

Its nice country because of the view, but its darn cold in the winter. Id take Texas any day.

 

I love texas highways, moving from up here in St.Louis to New Braunfels in the near future.....when me and my girl drove down there last summer in my vette, plus me being a cop lol....well we got on some toll way that was posted 85 mph....my girl just said....oh my, and grabbed the oh ***** handles lol.