How much experience do you have with hand guns? Most handguns are much less accurate then people realize and trying to fire one while you're driving, through glass, will lower that (already small) accuracy considerably.

Even if he hit the car, the chance that his rounds were going to hit the driver were very slim. I'd be surprised if any of his rounds didn't go past the car.

For that reason, it's negligent in the sense that he very easily could be sending rounds towards civilians in other cars or their own houses. One of the MAIN safety rules of any firearm handling is to be conscious of what is in front of and beyond your target.

I'm glad this Officer was willing to aggressively attack this guy and bring him to justice, but firing through the windshield was a bad idea. You can find several informative YouTube videos about how firing through a windshield would affect accuracy.