[ASOC]

Colt makes a 9mm 'M-16" lookalike, also in 7.62X39 and others IIRC.

[GSlob]

Same problem - shooting from inside the car would require swinging the bulky firearm around and bringing it towards the window - an awkward and time consuming proposition for everything with a non-collapsed shoulder stock. The policeman would have an ample time to react and draw his sidearm. And IIRC, assault rifles have projectile energy >1000 ft-lbs, while even a hot 9mm round from a moderate length barrel would not produce more than 600, and normally less.
That's why I'd think the perp was using a regular 9mm pistol, and assault rifle nomenclature comes from the reporter's gross ignorance.