I drove up to Alabama from Central Florida this past weekend. We took backroads (no interstate). I had reset the fuel mileage computer at the start of the trip and by the time I arrived in Alabama I had averaged 20.6 mpg. We drove the interstate on the return trip, I had the cruise set on 80 through the panhandle and by the time I turned south my average was down to 19.8, I expected that due to the higher speed. Here is the confusing part, after turning south, the traffic was moving much faster so my cruise was set between 85 and 90 for at least 2 hours. My average mileage went up to 19.9. It appears that my truck gets better mileage at 85 to 90 than it does at 80.
Could this have something to do with aerodynamics, or is the engine more efficent at the higher rpm?

I have a 2010 f- 150, 4.6 3v and 3.55 extended cab 6.5 ft bed

Has anyone at Ford ever experimented with this?

Kevin

 

wind direction could be a factor

 

Your fuel mileage should be fairly well diminished at speeds of 85-90. You can't always believe the computer, but I use mine to try and help me be more mindful of how I am driving by seeing how high I can keep the average. The very lowest speed I can get my truck to shift into 6th is 41 mph indicated. I drove along for a few miles after resetting my average mpg computer once I got rolling and it was cranking out around 32 mpg until I finally had to stop at a light. It started dropping fast even while sitting at the light. My guess is that at 85-90, your truck would probably be getting closer to 16-17 mpg. Driving the speed limit should get you 20+ mpg.

 

I drive my 09 Platinum 100 miles a day (mostly) on the autobahn here in Germany. I'd venture that you were going down hill with a tail wind to get that high over 80. I've driven mine for my commute at all speeds and found:

60-65 @ 20.1
70-75 @ 19.4
80-85 @ 18.2
90+ @ 17.0
P.S. I run Royal Purple motor oil and a K&N Drop in Air Filter. It DOES make a difference

 

Actually your speed makes a difference. The K&N Air Filter is just a sugar pill that makes you believe.

I used K&N air filters on all types of vehicles and there was no significant MPG increase. I'm not wasting my money on anymore K&N products.

 

When I run 80 and above, I get 15.5. When I run between 60 to 70 I get 18.5. Aero plays a big part in this. These things are a block at those speeds. Also, more rpms means more gas consumed even if the engine is not having to work as hard at higher rpms.

 

if you drive those speeds on the autobahn 95 you'll get rear ended...

 

It would be my guess that you got better mileage running at a higher speed because you had a head wind behind you instead of coming into you.I have noticed this before myself.

 

You could be right. I was getting high 17s to low 18s. After 2500 miles I switched all fluids (Engine oil, diffs and trans) to Royal Purple and put the K&N filter in. after a week I noticed a nearly 2mpg and kept it. I've got over 34K on it now and stay around 19.2

 

Wow, that's pretty impressive.

 

its more likely you got better mpg cause your engine broke in. I personally dont like RP. its to thin and made my car run worse than before.

 

Look at the map - if you are heading south, it means you are going down, so the pull of gravity will be helping you along. That's why the mileage is higher.

 

Yeah, but... yer also heading towards the equator where the world spins ever faster to the east. So, you also need to steer a bit to the right to compensate, or else miss yer destination

MGD

 

going south would also cause the wind to blow up you tail pipe

 

Can't make horsepower unless you're burning fuel. Why worry about fuel mileage at 90mph? Go out and buy a Hybrid car if you want fuel mileage. You want to go somewhere with a truck, fill it with fuel and go. Don't be so darn cheap!!