I have a Crew Cab 4X4 with the 4.6L 3V 6 speed auto with the 3:73 rear end. The truck has a little over 8,000 miles on it. Stock wheels and tires with no lift. I recently made a 665 mile round trip and my milage was 16.8 mpg's. This was all highway using cruise control set at 70 - 75 mph.

I thought my mpg's to be a little low. What have others that have this same set up experience ???

This is hand calculated. The read out on the dash said 18.4 mpg's when I filled up.

 

I haven't gone on any trips yet, but with my 05, the mpgs changed dramatically when cruising at 70 compared to 60. It wasn't a 4x4 but I would get about 20 cruising at 60 and 17 cruising at 70. The faster I went, the worst the mpg would get.

 

More true than many realize. I don't mind speeders or those who just tend to drive fast as long as they are within the capabilities of their equipment and skills (I'm one of them, particularly on a motorcycle or in an aerodynamic car) but it makes no sense when people drive fast in a rig with big frontal area and then wonder why their fuel range is low!

The drag of a vehicle increases by the square of it's speed through the air. That is why a ten mph tailwind can increase your range by such a large amount. For example, when cruising at 60 mph with a 10 mph tailwind, your effective speed through the air is only 50 mph. If your drag is 360 units (60*60) at 60 mph, then it is only 250 units (50*50) at 50 mph. And because the rolling resistance is but a small fraction of the drag, this makes a big difference in the amount of HP needed (and thus fuel consumed) to maintain a steady speed.

 

I just went 609 mi on my last tank, added 34.5 gal = 17.65mpg. Close to 450 was highway 65-75mph, trip included some 4 wheelin too. I am content with that. When I decide to settle down and set the cruise on 72, I think I will top 18. Daily driver 30 to 50 miles 25-65 mph averaging between 16 to 16.5. Note: the cpu has consistantly been about .4 higher than my math.

 

Thanks for all the replies guy's. Anyone else have any input ???

 

My 09 has about 5600 miles on it, all highway. Most trips are 70-75 and my best has been 18.2, lowest 16.5.

 

My extended cab 4x4 has the 4.6 3V. i drive about 50-75 miles per day, 60-70% highway traffic and have been getting right at 17 mpg.

My dash says that I have been between 17.5 and 17.8. This time it says 18.0, so I will cross my fingers and hope for better.

 

Wow, 4x4's are out performing me! Any mods on thse vehicles? I have a 09 XLT 4.6L 3 valve with the 6 speed auto tranny stock at just over 8,500. I travel to and from work for 14 miles each way and about 90% of the time, the tach is below 1500. Yet all this and I yield only 16.8 mpg. I am looking into a tuning mod for the PCM. Since I bought it new, I ran the 3000 miles then switched to Royal Purple 5W-20 Synthetic. I have also noticed the mileage peaked at just over 20mpg when it had only a 1700 miles on it. Since then, it has stablized at 16.8 mpg.

My goal is 20mpg or over. Researching mods now to make it happen.

 

Damon have you reset your on board mpg computer? I think the manual mentions not being fussy about mpg until 5 or 10k miles, can't remember exact #'s. I have 9000km's and will be resetting it at 10k and again at 20k, and making notes along the way. After owning 6 new veh's in the last 16 yrs I have realized better mpg once 20000km's are reached.

Terrain, speed, load, and driver habits are probably biggest factors in mpg's. Travelling at 55mph (90km) is optimum in my SCREW 5.4 4x4. The speed limit on our main HWY is 60mph and I usually travel 70+ which does not help. But I didn't buy this for mileage, I bought it for safety and to haul toys, and because this new F150 kicks A.S.S!

 

Thanks for the Tip! Looks like time to read my manual. I think after reading this forum thouh, I am definately in the market for some tuning.

Funny thing after posting this last night, I drove home from work and the computer poed back to 17.0 MPG! Must have gotten jealous. But, I drive with flow of traffic. Try to minimize brake use and keep cars clear of my ride!

I read in anoter forum that a taneau cover will yield up to +3gpm. Anyone else get that?

 

No bed cover will increase FE in today's vehicles. Also, running with the tailgate down will likely use more fuel than up as well. There was a Mythbusters study about that, so search for the video.

The only way to reliably save fuel is use less accelerator pedal. Tuners offset any fuel savings (which is rare for stock size tires) with the requirement of premium fuel costs 10% more.

 

Why do you say that? I saw a quote a few days ago from a guy who had worked on aerodynamics with (or for) Ford and he claimed covered beds resulted in lowered drag coefficients in their tests.

 

So has any owner actually saved money on fuel by adding one? I have never read it. They do add weight which has a negative impact in the city, although I suspect immeasurable.

My brother claims about 10% better FE on the highway after he added a full topper after owning the truck for 60k miles.

 

I assume you mean "3mpg". No, you won't get that much, the tonneau manufacturers do like to exaggerate the potential savings because it increases profits. I would expect a slight increase in hwy mpg and a slight decrease in city mpg (due to the extra weight). Nothing that could be measured very conclusively without specialized equipment.

The biggest benefit would be realized by those who travel long distances at speeds above 65 mph. From the various data I've seen I would estimate somewhere around 1% fuel reduction on the hwy or less than .25 mpg improvement.

 

If a tonneau reduces the drag coefficient of the vehicle at hwy speeds then it is a scientific certainty that hwy fuel consumption will decrease. It may not be a big difference, it may not be enough for the average driver to notice, but it will decrease fuel consumption.

Aerodynamics are often elusive and somewhat counter-intuitive, But I've seen evidence from more than one source that showed a canopy significantly increased aerodynamic drag so I would tend to attribute your brothers apparent increase in mpg to other causes (unrelated to adding a canopy).

However, trucks come in all sizes, shapes and slopes. It is possible that a canopy could reduce drag, perhaps if the attitude of the truck (front and back ride height) were such that a canopy helped. I would not expect this on a truck that rode relatively level. Or, perhaps the canopy was very heavy or encouraged the carrying of more stuff. This could increase mph simply by squatting the back end into a position with a more favorable drag coefficient.

My Volvo sedan gets measurably better hwy mpg with about 300 lbs. in the trunk. This is likely due to better aerodynamics by bringing the underbelly of the vehicle level with the road. It is amazing what a slight attitude change can do for aerodynamics and it can make a real difference in fuel costs in extended driving.