Just finished our first road trip... 2018 Platinum Expedition 4x4, went from central Texas to Port Canaveral, FL, then over to Orlando, FL and finally back to Central Texas. No towing involved but 4 adult sized folks with a full complement of luggage in the back for a 9 day trip. The speed limit on I-10 is 70 mph for most of the way, so I had the cruise control set at 73 for 90% of the trip, I also used regular unleaded (87 octane) exclusively for this trip and the ECO driving mode was used for about 95% of the trip. I ran in 2H mode for most of the trip, but coming home we ran into some bad thunderstorms so I engaged 4A mode for about 60 miles, interestingly running in 4A mode did not appear to impact MPG at all. Having a couple of teenage girls on board meant that there were frequent stops along the way to "freshen up". Here are the numbers:
Trip Time - 39.31 hours (62.35 mph average)
Miles Driven - 2451
Average MPG - 20.8
Best MTE seen - 521 (22.36mpg)
Best Fuel History - 20.9
I am not sure what criteria is used for the calculations, but as you can see the Trip computer, fuel history and MTE all had different values. All in all the 2018 Expedition did fantastic and in my opinion was the most comfortable and easiest vehicle to drive that I have ever owned. We did have one annoyance on the trip, the rear drivers side tire pressure sensor stopped sending info 5 or 6 different times during the trip throwing any error up on the Driver Info Screen, however the sensor would resume sending data again after a couple of minutes and work normally again for a while.
While none of this information or data was collected using scientific methods, I do feel like the numbers are realistically what most folks can expect on long distance non-towing road trips.
YMMV,
dusty