I used to disconnect the "HOT" lead to the distributer all the time on my 406 powered 76 Camaro. Glad I did to cause one night at a "freinds house" his friends got the idea to joyride my car while I was "passed out" (I woke up the first time they hit the starter, but just acted like I was sleeping) about and hour later of starting (god bless 990 CCA) with no luck I get up and they tell me, "your car won't start". "No kidding", I tell thim as I open the hood, hook up the lead, hop in the seat and hit the key. "See, theres nothing wrong with it" I tell them as I drive away.

 

My old Jeep has a toggle that would turn off all the running lights (located near the back bumper); it also had an on/off toggle for the electric fuel pumps. Whenever I parked in a sketchy area I would hit both switches. A thieve will not find it comforting stealing a car vehicle at night with no lights, and on top of that running out of gas about 1/4 mile away. It also had a break lock handle; the more you pump the breaks the more it holds.