Driving like I had an eggshell between my foot and the gas pedal got me around 19.2 mpg after 500 miles. Just now, I drove about 5 miles in the city and 15 miles going 70 mph and my truck got 20 mpg altogether.

I have 3.55. What is the optimum speed? My older 2012 with 3.55's got decent gas mileage at 55 mph, usually around 25. The new truck is longer and I could kind of swear gas mileage improves when I hit 65, maybe 70....

Anybody else getting the same thing?

 

I have gotten as high as 25mpg on the gage,, driving very carefully at 60 mph. Faster than that it drops off, into the 17's but still at times seems it comes up a bit at 80 mph.. Seems to depend a lot on the temperature and wind speed and direction.

 

The rpm where you make peak torque is where your engine is most efficient at converting gasoline to energy.

Sometimes there is a point where going faster can increase the mpg. There are way too many variables to predict what happens each and every time.

My V10 gets better mpg in the hills. I gain more advantage going downhill than I lose going uphill. I've seen some of my best empty mpg driving in the hills / mountains. I've read this is common for high torque at lower rpm engines.

 

Torque peaks at 4,000.. I'd have to be hitting 100 mph.

I tend to hit 75 going downhill and 50 going uphill. I don't do 60 constantly. I am told doing the same speed uphill and downhill is not good for the gas mileage. My commute is hilly so I don't use the cruise control.

This day, I was driving quite a bit faster and noticed it didn't affect the gas mileage as much as I'd thought. 70 mph instead of 55.

 

Defying physics if you're getting better mpg by driving faster. The 500 mile stretch is much more believable than a 20 mile run.

 

I tracked the mileage of my morning commute all summer and experimented with different settings. My 20 mile commute is fairly short, but the return trip during the evenings is completely unpredictable. Every once in awhile, I'd get a very strange result...the MPG would be higher or lower than what my averages suggested it should be. It's was as if the truck could dial the MPGs up or down 5%. I've yet to figure it out, but I'm thinking part of the variability is the trip computer itself. We all know it's rarely accurate or even consistently off the actual value.

 

I got an indicated 99 MPG one time when starting from a fresh fill of fuel, and driving downhill from an elevation of 8,000 feet. It was a mountain road (obviously), so going downhill from there, it was indicating 40+ MPG for quite some time. It wasn't until we got down to lower elevations and the pure downhill turned into rolling hills, plus getting some traffic. It wasn't until we started some stop-and-go between Jackson and Columbia on highway 49 that it got down into the 20s. By the time we got to the SF Bay Area, it was indicating 23 MPG. (grain of salt, our lie-o-meter is typically 5% high in what it indicates)

 

I know about the elevations and all that, but my 20 miles going from the same Point A to the same Point B would show 20 mpg going 55 mph and on the way back, around 24.

That's because there are several steep downhill roads and I have to brake. Elevations in both points are identical although it's very hilly between the two. Hitting 70 to 75 mph, I assumed I'd get 16 or 17 mpg but was surprised to see 20.

Still trying to find that "sweet spot" - my 2012 with 3.55 was at 57 mph so I kept it there. The new truck... still having a hard time. Going 55 mph, I got far worse gas mileage than my 2012 so I'm trying 70 and it's surprisingly similar, maybe slightly worse, but not much worse as was the case on my 2012.

 

At what speed do the grill shutters close?

I'm willing to bet these trucks are tuned to have the best MPG at whatever speed the CAFE tests dictate.

 

I was told engine shutters are a little gimmicky. The wind can either stop at the grille or at the engine if the shutters are open. Either way, wind is still stopped and the truck has to work harder. Aerodynamics is the biggest factor at 70 mph. I agree, Ford is maximizing the gas mileage at any cost. I think that's why the current Goodyear Wrangler tires are a little more slippery than my 2012's Michelins.

 

Are these the first 500 miles? If so, recommends in the Owner's manual that not to be concerned with MPG for the first 1000 miles due to break-in.

I'm sure once you crest those first 1000 miles...the MPG will settle down some...and become more accurate.

Either way...it is nice to see you finding the sweet spot of your F150.


biz

 

Not necessarily. If the engine is lugging at a low RPM, it might become more efficient at a slightly higher RPM (due to better exhaust scavenging), even enough to overcome the added air resistance at a higher speed. Your post is an example of why people should be careful about making blanket statements about subjects they don't understand. The intake and exhaust systems work on physics, too. Good scavenging is an extremely complicated process, because it involves the entire intake and exhaust system, the cylinder heads, the injection timing, and the valve timing. And it still matters with DI, because it's not just about pulling in more air/fuel, but about getting the spent gases out (although modern systems are designed to use some exhaust gas to reduce combustion temps to reduce NOx compounds, which is stupid IMO, but that's a whole other subject).

 

It's the bubble effect that helps the mpg when the shutters are closed compared to having all that useless air going into the engine compartment and then getting dumped under the truck causing even more drag..

 

First 500 miles? No, more like the 4th 500 miles (I have 2,400 on the odometer). I am starting to think going 65 to 70 mph is the sweet spot for my 2016, but I have to run a few more tests. My 2012 was definitely 57 mph.

I know gearing is also a factor when it comes to fuel economy, too low or too high can affect mileage. If I quickly accelerate while it's at the highest gear instead of downshifting, it may also be bad for mileage. That is what is complicating my efforts to find that sweet spot.. going 55 mph is probably not it.

I always thought the bubble effect was trivial, not as helpful as aerodynamics or even allowing the air in so that air can go all the way to the back and leave the car. That's why there's the vent next to the hood, so air can escape upward.

 

Your joking right? Thanks for sharing your knowledge of a modern DI internal combustion engine by the way. It's as extremely uncomplicated as you seek to make it. 6,000lb plus truck will NEED more fuel to keep it moving 70 mph vs 55 mph. There's no engine tech in any Ford truck that gets around my uninformed blanket comments.