Introduction: DIY RFID Car Starter Kill Switch - Complete
More info www.matthewrichey.com/car/killswitch
Time delay relay video: http://www.youtube.com/watch?v=1CnnC-m8zuA
Basically it's a 27 seconds time delay relay, RFID tag system (has 1 LED), project box from Radio Shack, some wire and heat shrink.
if you have any questions let me know.