The DTE is different based on the capacity of your tank, axle gearing, and your estimated mpg. i have 36 gal. capacity and 3.75 gears and get 16.7 mpg normal driving, so based on your mpg and the last 50 miles before empty, you might have more or less then 5 - 8 gallons left. Those with the 3.31 gears will have better mpg's.

 

I think my truck has a 23 gallon tank. Correct me if I am wrong. When I fill I let the pump click off. I do not top off.
I do not watch my miles to empty much.
Many times the orange light has come on saying I have 50 miles to empty. I click OK.
In 211 fill ups the most I have ever put in the tank was 19.777 gallons.

 

We don't know what truck you have so we can't answer your gallon question.

The DTE is likely to never ever match the MPG display you see.
Read the thread, it is based on recent history. If you drive like a robot, you have a chance for DTE to be close.
The display you see is based on an average of I think 30 minutes. If you ALWAYS drive the same, sure it could resemble an accurate number. As soon as you drive like grandpa or drive like you're on a race track, you've confused the DTE system and will no longer be accurate.
It's just a dumb number they put on there that isn't accurate.
I have a 36 gallon tank and it can read nearly 700 miles. If I drive in a straight line for 700 miles with no change in speed or wind or heat, the average would be fairly accurate.

In 2016, the 4x4 Lariats were equipped with 24 or 36 gallon tanks.
If you don't know your capacity, you yourself can't estimate the DTE either. Wait for somebody to provide you into about what size tank your truck could have -but first tell the people what you drive and what options you have such as max tow, fx4, lariat, etc.

 

AFAIK, since the DTE is based on the computed MPG, however far off your MPG is, will greatly affect your DTE.
So first, manually compute your MPG over several fill ups and log that along with the truck computed MPG.
Then average the groups of data to figure the percentage off the truck computed value is from the hand calculated MPG.
UsIng the engineering dash mode per the procedure here on the forum, adjust the mpg bias by that percentage off. That will make your DTE displayed closer to reality.
As a well trained submariner, I want my gages calibrated as well as I can to be able to believe their readings.

 

DTE is designed to reduce the moron factor. That's the person that wants to see if they can fit 26 gallons into their 26 gallon tank (or 23 gallons into the 23 gallon tank or 36 gallons into the 36 gallon tank). To fit that much gas the tank has to be empty, meaning you ran the fuel pump dry, possibly burning it out, and perhaps didn't make it to the gas station.

Ford allows for the truck to go to zero miles on DTE and have spare fuel for the moron factor. It's not advised to run your truck to that point and test the theory. Each tank has a few gallons of spare fuel, it may differ from the 23 to the 36. As I recall, the 36 has like 3.5 spare gallons.

 

Read my post you quoted. No where did I say anything about MPG. I did say I don't look at DTE much so I wouldn't know if it matches my MPG or not. Don't care.