Well I'm not going to run my car out of gas but I can give you a very good estimate based on known parameters of my car, at 350 miles I put 14 gallons back in the tank, that comes out to 25 miles per gallon which is very consistent with my car, so using that it's easy to calculate, 15.9-14=1.9×25=47.5 miles till you run out after the light comes on. But we all know that that is not chiseled in stone because of driving conditions and Driver input. But based on that if you hit 397.5 MI you better be looking for a safe place to pull over, hopefully it's into a gas station, 😉