I have had some thoughts *I dream alot when I'm finding problems at work* about how I could immobilise a car to the point where a theif is going to be scratching his brain for quite a while.
I thought about the common one Fuel pump cut, then the possibilities are endless, once he finds the fuel pump cut off, then he would have to diagnose why there is no spark. Then he would have to work out if the cut has been at the ECU or the Crank Angle Sensor. Then once he got it going, im not sure if the oil pressure switch on a skyline will shutdown the motor but I would say it would have a detrimental affect to what the computer reads....
Then he brings a tow truck.
Cheers
Sumo