Plug in and Stay

There is this cool system here whereby you can hire a car for just an hour or so if you wish. This is one of those cars parked up near where I live. The cool thing about this one is that it's electric and it has to be plugged in to charge.
One thing bothers me though, what happens if you take the car out and run out of charge without being near a charging unit?? I'm sure someone has thought of that.