Could have also been a situation where he didn’t have time to stop for gas if trying to catch a flight, and erroneously thought that he could make it. May not have been intentionally trying to save money as the reason.
Or it wasn’t accurate. If it’s not your own car, you might not know the gas gauge as well. I’ve had cars that say they have a 1/4 of a tank and all of a sudden the light comes on.