I know someone who had a toggle switch hidden under the dashboard of his '63 Chevy sedan. It operated a relay that closed a valve in the fuel line near the carb. He did this after someone tried to steal his car months before.
He was vigilant in turning off the gas whenever he parked his car. To make a long story short, thieves stole the car and there was just enough gas in the carb bowl to drive the car about a block and behind a cemetary. The thieves took the seats & radio and a few other things out of the car and smashed every window in the car.
My friend gave up after that and junked the car.
