Another reason to use cruise control is if you have a heavy foot to start with. Not a huge deal with my F-150, but if I didn't use it in my Tesla, I'd be getting too many speeding tickets.

 

If you have an electronic rear locking axle If it is a 4x4 you pull out on the 4x4 ****. not sure on 2 wheel drive.
TJ

 

In case interested...

2wds with Elocker just have a **** for the locker in place of 4wd

 

My 2016 5.0 was the same, I easily got 1+mpg better with my right foot versus cruise control.

 

Cruise control will only save gas if your a heavy foot and don't lift the foot when it's not needed.
Cruise Control is pegged to speed set. Up a hill will try to maintain that speed. It uses more fuel. Down hill the throttle closes and you get the fuel aveage returned to the total average, just used.
A plus in fuel use and a minus use equals zero gain in milage on a one way trip in places that happens..
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Not that is of any benifit other than observation, at fill up, zero out the last average. Then pull away from the pump and go down hill and see the average roll up to a very high number to show how the system works, then come back down as you drive, to a normal fuel use level for your driving.
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Do this if you want to get the best mileage driving over a course.
Call up the aversge fuel milage screen "water fall". A wide green area that moves with throttle position and vechicle motion.
While driving, try to keep the top of the green above the line as much as possible.
Doing this will require you to lose some speed in certain areas as you drive.
No different than watching a Vacuum gauge for highest Vacuum in the old days to get best milage the vehichle had to offer.
You have these features you paid for, use them if your concerned about fuel mileage.
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I have obtained as high as 22+ mpg ave. on a 140 mile round trip up the mountains and back down on a 2018 5L with one passenger and could get more if I drove slow enough the get in others' way. Were talking about a bit over 7 gallons of gas refill back at the same filling station.
Continiously repeated time and again. The mpg system function works very well.

 

FWIW the 2016 F150 is the ONLY vehicle I have gotten better mpg normal driving versus cruise control. To each their own I suppose.

 

I was thinking that, I knew I had seen it while reading the manual. However since it didn't apply to me I promptly disregarded. It wan't important enough to go drag the manual out of the pickup and look it up.
TJ

 

The reason it acts that way is because it is. Even forced induction engines have vacuum when the throttle pale closes. However they don't make enough to work all the items that use vacuum which accounts for a vacuum pump on these vehicles.
TJ

 

Ok, I checked it today and my 2020 XLT does not have that feature even though it is 4x4.

 

No worries - I keep a downloaded PDF copy on my computer and phone to quickly look things up with search. The paper copy has never left my glove box.

Default 4x4 configuration is without the Elocker. Nothing out of the ordinary