I have a keyless lock for my front door. My kids are CONSTANTLY leaving the front door open. I lock the house doors whenever I leave, but I leave my car doors wide open. I NEVER leave anything in my car because I had 2 cars broken into, one, they stole a CB radio, but left the in-dash, and the other, they stole some crap from my glove box that was worthless (but left an envelope full of cash that my passenger had left in there, unbeknownst to me). Consequently, I no longer lock my car doors, hoping that the assholster who wants to steal something from my car will try the door first.
Seriously, NEVER anything in my car worth stealing. Brake fluid, quart of oil, transmission fluid, power steering fluid, that's it.
Howsabout you (and why)?