I rent quite a few cars at a local agency and a couple years ago, one of the guys behind the counter was telling me about a recent auto theft..... The fellow behind the wheel of the stolen car pulled on to a freeway with a cop in an unmarked car somewhere not too far behind him. A few exits down, the car thief pulled onto the off ramp but got caught in some bumper to bumper traffic. Once the guy was at a dead stop, the cop radioed to somewhere and onstar shut the engine down. The cop basically walked up to the car before the guy had even opened the door and arrested him.