Your G will beep at you if you walk away with the fob while the engine is still on. Yes, the car will still work. It comes in handy if you're in the situation where your friend needs to borrow the car, but will return it to your house (without ever turning it off, of course). At first, I thought this was the biggest safety risk. But, if you think about it, a car-jacker can do the same thing if you leave your keys in a car without intelligent key. That's even worse, because they'll drive away with the keys.