On my 2008 Honda Fit Sport automatic, the gas light comes on with around 1.2 gallons of fuel left. Hills can trigger it earlier. When does it come on for you guys? Wanted to see if there is a spread.

 

The steering wheel blocks the light on my 2017

 

1.0 ~1.3 gallons is about right. Yes, hills can make it illuminate earlier.

Don't run it down too far. Remember, the gasoline cools the in-tank pump. Once in a while won't hurt it, but long term you may reduce the life of the fuel pump.

 

I've noticed a similar range of around 5 liters (L) = 1.4 gallons of gas in my case, but I've got the GE (2nd gen) Fit if that makes any difference. And this is only a 'guesstimate' based on the specified volume of the gas tank (40 L) - in real world applications we should also account for the entire length of the gas filler pipe as well, not only the tank - which in the case of our Fits is quite a long pipe that stretches to the front seats and can add anywhere from 1-3 L extra.
Either way, as a general rule of thumb, the triggering of the gas light is never based on any accurate specific volume of gas leftover in the tank. Factors like temperature and hills will trigger the gas light to come on sooner or later than the average.