I bought my F150 primarily for pulling a travel trailer. Before I get my trailer out of storage I always fill the gas tank and the distance to empty display resets and provides a new reading. The new D2E number ranges from the low 400s to over 600 miles. My question is what is that reading based on?
My truck has a 36 gallon fuel tank and if my display shows my average MPG to be 19 then if the number were based on that the D2E should display 684 miles. If they subtract a reserve fuel amount of say 5 gallons for the calculation it would still be 589 miles. Then I hook up my trailer, reset the average MPG and start down the road and after say 20 miles my average MPG is now around 11 or 12 MPG but the D2E is still reading in the high 500s when I know that at best I only have about 430 miles to empty so it doesn't seem like the D2E calculation changes until the next fill up.

 

Distance to empty is calculated based on your past X amount of driving miles' mpg. That's it. It accounts for towing vs. not, but it's not super accurate. If all you do is drive the same way day after day it will be pretty accurate.

BUT if you're like me when you drive very erratic trips (in town, highway, towing, etc) with no pattern, I've found that number to be pretty useless.

 

Above is correct, you could have a 19mpg average bur the last 30 miles (I think it is 30 miles?) could have been an average of 14 due to in-town driving. Your new DTE is calculating part of the 14 that you're getting now.

DTE based on the average miles is more misleading than the current miles, just as you say.... if you had a readout of 684, you would soon realize that you can't reach that distance at 14 (current), not the average that you had before you started hitting stop/go traffic or driving like a mad man.

If Ford had economy worth bragging about I could see them posting the DTE but MPG is so lousy they should omit that from the display.

 

Are you changing the DTE from normal to towing in settings?

 

This ^^^

Doesn't sound like it.

You should be using the truck's menus to setup your trailer, and then switching to the trailer if the truck doesn't automatically. Then, DTE should somewhat accurately display trailering. When you disconnect, make sure it switches back.

 

I thought I'd seen all the available settings and never saw that one.

I have setup my trailer in the menus and when I attach the trailer to the truck it automatically displays that my trailer is attached and when I disconnect it shows that a trailer is no longer connected.

As I said above I thought I had found all the available settings but obviously I haven't. I'll have to spend more time with the display and try and figure out how to reach some of the settings that are not directly accessible using the arrows. As an example for the first year I owned my truck I never saw the display showing which gear I was in and then one day there is was. Now it's gone again. I looked and couldn't find out how to get it back. Simply following the arrows and pressing the OK button doesn't seem to get me to all the available settings. I must be missing something. Having built my own computers and written my own computer programs I'm usually pretty good with this sort of thing but I'm obviously missing something.

 

Push the + or - button on the shifter...

As to the DTE menu, connect the trailer and you should be able to find it.

 

My DTE is dismal at best. It does change when I connect to my trailer, but the update frequency and methods they use are, well nothing like my previous 2005 gmc (one of my disappointments with this truck actually). I hear some say theirs work well. Now on a long trip, like 400+ miles, mine will present itself better, but the DTE is still off by a few gallons. I have little to none reliance on it. No trailer, 700 miles; with trailer, 250 miles, between hwy fill-ups, using 89 octane

 

One must always remember, DTE only know past. Can not predict future.

 

My Distance To Empty (DTE) lies to me. It'll warn you when you're down to like 50 miles. Then you fill up the tank, 26 gallons, right? So you're thinking it's gonna take like 23 gallons, right? Nope. 20-21 and full.