FYI for those who stated that the car should turn off when the FOB is no longer in range, there's actually a good reason for that and is not a design fault.
Imagine this scenario. You're driving down the highway at high speeds. Your FOB battery goes dead. Should the car then shut down the engine because it can no longer detect the key?
That's the main reason why it doesn't kill the engines immediately but only prevents restarting of the vehicle when the key is out of range.
Always remember... when something seems like a fault... they'll always say its a design "feature"