There are several different ways to get the numbers. Honestly whatever blows your hair back. I've religiously tracked my mileage for years in all my vehicles every fill up. Like mentioned here, I don't let mine run all the way out... I usually fill up around a 1/4 tank too. But I track it with the actual mileage.. and over time you get a good picture of the average mpg your jeep, car, motorcycle, whatever gets. So that way with continuing this process, if I start to see a drop off in mpg, with no other unusual cause, like a tank burned going off on trails when I normally don't.... then I know to start looking for an issue while it's small before something breaks or it gets out of control. It gives me peace of mind.

I have to share that I do run it dry every time I get a new vehicle. For two reasons... Need to know how long it takes to pick it up again, and how many miles after it hits the empty mark it will actually go.

reviving a post from the dead. I do believe i fixed my issue once and for all i noticed i had a lower end on the vacuum pressure on my engine so this took months to find until today lol i poked my head under my jeep on a lift and doing an inspection im looking and noticed a rubber line has rotted away going from the gas tank to the evap charcoal canister so idk how i missed this but i stuck a new line on it and omg my jeep feels like a muscle truck i got alot of power back and i do believe my mpg will also fix itself with this too i need to do a vacuum test to confirm but this seems like a right step in the path lol.

Back from the dead. "EEVEE" I love your choice of words to describe the power haha. Brought some joy to the evening.

*pokes the gas needle* h-hey are you still working?! i mean 70 miles and you havent moved much there buddy.