My fuel gauges only know full and empty. I always take a new vehicle and run it low as possible then see how much it takes to fill it. I run lower each time until I have come close to running it out of fuel. Once you run it low and know where the gauge reads and how much fuel it takes at that point, you have verified the accuracy of the gauge. My wife is the master at running low on fuel. She never runs out, but it always comes within a half gallon or so of the tank capacity. I have run out several times, but always had fuel with me when I push it. I figure it has a 34 gallon tank, so might as well use it all.