I don't think it's a good idea to run your tank down so far. Fuel in the tank is used to cool the fuel pump. Good chance you'll kill the fuel pump if you do it long enough
My light just came on when it ticked down to 20 miles range. Since I have NAV, a pop up on the NAV screen also asked if I wanted to search for a nearby gas station.
We had the 2016 forte down to nothing. Cruised into the bjs and filled her up
All 12 gallons. 15 gallon tank. Dunno where or why the 3 gallons weren’t recognized.