Ok dress head to tow in black or asphalt grey and find a good vantage point like a rooftop. Then use a fully suppressed 22 rimfire rifle with night vision scope and start popping people as soon as they get within 50 feet of the car--thugs, joggers, old ladies, dogs--you drop em if they even give a passing glance from 150 yards...
Well, instead of a gun to protect a piece of metal in a parking lot, why not get a video cam, hide it and catch the suckers on film. Then let the police take care of them.