Some time ago, I drew up a circuit diagram for an anti-theft device that requires the driver to push a hidden button to energize a magnetic-hold circuit to complete the ignition circuit from the key swich to the coil. Anytime the key is turned off, the system resets itself to the "won't start" default position. It involves using two of the small square Bosch relays and a momentary-contact push button. Even if a thief manages to bypass the ignition switch or steals the keys, the engine won't start without pushing the hidden button.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!