Several of my friends got into a discussion about this topic. Is there any potential damage to a car to consistently wait until the fuel light comes on before refueling? My stand is no. Correct me if I'm wrong....I believe the fuel pump works harder when the tank is empty. But there is still a safe reserve to get to a gas station. If there is any damage by waiting, automakers would have built-in a safety margin. That safety margin is the light, reminding you to go get gas. Their daddy sez you should never go past 1/4 tank because it will suck in dirty contaminants into your engine. Is there any truth to this? Any mechanics out there?