Winston wanted to make it clear that he did not want the cop car near his house. So he attacked the car, and literally ripped off the bumper and punctured two of the tires. The cops did try to subdue Winston, first with pepper spray, then with a tazer, but he was determined to take out that bumper. As you can see in the video below, he did have two buddies cheering him on, but Winston did nearly all the damage on his own.
This got the dog in a little hot water, and he was detained at the McKamey Animal Trust for two weeks to determine if he was a dangerous dog. He did display good behavior during that time and has since been released to his owners--who agreed to fortify their fence and take Winston to obedience classes. He will be on "probation" for another 6 months.
I think Winston was just trying to look tough in front of his buddies, but he was lucky the cops kept cool and did not take more extreme measures in trying to subdue him. I hope he learned his lesson to not mess with the cops (or their cars)!