I've seen them used multiple times during live cop shows.
In one instance, they were using a dart that had a huge magnet on it so as soon as it hit the trunk, it stuck really well and all the cops backed off and they then had a chopper follow the car back to the owners house where they made an arrest later in the program.
In another instance, the guys clearly knew what the cops did, because he ducked off the highway into a residential area where the cops had several calls of a car that pulled into their neighborhood at a high rate and four dudes jumped out like a clown car while the car was still in drive, which then ran over one of the residents mailboxes. They got three of the guys within minutes as they swarmed the area, set up a perimeter and boxed them and then brought in the K-9.
Even the cop said car thief's know the cops are using this tech and since they were also using the magnet, it makes a very loud "thud" when it attaches to the car's frame and thieves now will ditch the car and go out on foot to try and get away, making it far more easier to catch them as opposed to having to do pit maneuvers or other high risk moves to end a chase.