I've had the worst luck over the last year and half. This will sound like a country song to you.. but hold on tight. My car has been broken into 5 times and I was held up at gun point and mugged. Seriously!
Anyway... I'm soldering together a car alarm kit. I realize this is a little late, but better late than never.
Right now I'm driving around with two broken windows and broken glass all over the car. This seems to ward folks away from my car a little.