I think fuelly is a great real word asset.( though I think there are two 2021 trucks that say they are ecodiesels that are most likely gas , because they are in the mid teens) .I use my truck for combined mileage and for towing so my average is lower than it would be if I was only doing highway mileage. Having said that, when I embark on a trip that is going to be mostly favorable conditions for high mileage and not towing, usually I reset my trip and will get between 27-28 winter fuel mpg. I do use Fuelly and my '15 had every fuel up recorded and hand calculated (which is what Fuelly does) and so far I've captured every fuel up on my 2020 as well.
Unlike my '15 which was a very accurate EVIC mpg, the '20 is off by a couple mpg high so far.
a recent conversation with a friend had him saying he could get 22 in his Chevy on the highway. So my 27mpg was not very impressive. I told him my real world average was 25 in my 2015 bighorn,not my high. He finally came clean with his average , 14,mpg.
someone here mentioned setting up a second fuelly account for when we are trailering.