Two trypes of anti-hijack as far as I know. One is where the alarm auto locks the doors when the ignition is on.

Think the type Rick is on about tho is a system that cuts the ignition if you don't perform a particular function on the car at a particular time. Not sure on the ins and outs, but it brakes the car until it comes to a standstill then cuts the ignition..or something like that...lol