Thread: Turn your car off with cell phone?

Ok so say some one runs up to you when you are in your car and is like "get out of the car or i'm going to blow your brains out" so you get out and he drives off with your car. Is there anyway to interface your cell phone with the car computer and say using the serial port with a relay card to cut the ignition and kill the car? Just wondering if anyone has done this. I searched and will admit to sucking at searching so if anyone can help thanks.