I have come very very very close to running out of gas a couple of times, but never completely to where I could not move the car anymore.
The first time I was at a stop light and the car began to sputter like it wanted to stall, but i simply put it in neutral and went to nearest gas station and filled up.
The second time I was getting off the highway on an off ramp that was kind of uphill, and the car just almost didn't make it up the hill, it would almost stall, but at the last second, find enough to push itself a bit more, and eventually made it up the hill and went to a nearby gas station.
I don't know what you should do tho if you run out completely...I always thought you simply need to fill up gas and start it up.