Ran out gas/car won't start

In most newer cars the fuel pump is submerged in the tank and is cooled by the gas in the bottom of the tank. If you run the tank to empty, you take the risk of burning out the pump. I try to fill my tank to full when it gets below the half tank range. Doing so has an additional benefit during the winter too, reducing the amount of condensation space which can put water in the gas tank and make the car hard to start.