I know this question is very similar, but I am specifically talking about the fuel gauge and not an indicator light. Almost every car I've owned could run for quite a while with the fuel gauge reading an empty tank.
Is there some standard (either enforced or just customary) in the US for calibrating fuel gauges as to how much wiggle room you have after it technically says you are out of gas?
I know my own car's limits fairly well (at least as far as I have tested them), but I'm curious in the context of an unfamiliar car, for example a rental.