Most respectfully & I mean that sincerely, an odometer cannot ever be a good indication of fuel - or range - left.
It is a good generalization to use consistently to say 'better get gas NOW' which is great if you are close to gas stations; how about when you are on a trip, not sure if your average over that 120 (or 180) was 40 or maybe closer to 35 if you'd been 'on it'? And how much gas is REALLY left and can you make it to that next station that is 25 miles away?
That is why we have fuel gauges in our 4 wheel boxes rather than just an odometer

Honestly a low level light (assuming it works & often they don't!!!) is a better warning than odometer because at least it does not care what consumption was prior to that point.
The Fuelbot is great because it gives you exact range on what you have left at whatever your CURRENT consumption rate is - & with the instantaneous mpg reading you can ride at the precise speed which yields the best efficiency to get you to the next stop when you are tight spot