I disagree. I think it could be considered murder 1, because at any point, he could have stopped. It doesn't matter how long ahead of the shooting he planned to shoot the kid for it to be considered premeditated, right? Even if he thought, "I'm going to shoot him and teach him a lesson!" a split second before he started. He didn't accidentally shot this kid, it was an intentional act due to a situation that he brought upon himself. He could have stopped when he reached for his gun, when he took it out of his glovebox, when he had it locked and loaded, when he aimed, and any time after each of the first 9 shots. He didn't though; he decided to kill this person and he did. Even when the kids drove away, he ran a few feet away behind his car and continued firing at them.
There was no danger to him, except that maybe his undies would become permanently bunched.