My car came with a few systems that protect it from theft: door locks, purple paint, automatic nothing (except transmission), and the fact that it's a 1996 Hyundai Elantra. But today, by accident, I thought of another.
I left a bottle of Febreze in my car. So now potential thieves know that it's a purple 1996 Hyundai Elantra with manual windows, seats, and door locks, and that it smells bad (which it does--it still smells strongly of old people, even after a prior febrezing and much leaving-open of windows). It is just on the outside edges of possibility that someone might want to steal a purple 1996 Hyundai Elantra with manual windows, seats, and door locks (it's reliable! it has the optional air conditioning! it's reasonably fuel efficient! um... fits in most parking spaces!), but a stinky 1996 Hyundai Elantra? I don't think so.
I feel that I should get a discount on my insurance for this.