And as with everything we do these days, you have to consider the legal consequences of you or your cover officer shooting at the driver.
It's likely you will be able to legally justify shooting the driver, but it will be very hard to justify shooting someone else. What if you hit a passenger? What if you hit another driver in another lane? What if you hit a pedestrian? Before you fire that weapon be sure of what is behind your target.
Regardless of justification, in today's atmosphere, your actions will be over-analyzed by the media and the so-called experts and anyone injured in the incident will likely sue.
If you get sued and the case goes to court, what many plaintiffs' attorneys will do is "segment" or break down the incident into a number of steps and they will find one of the steps you took wrong. They will say this one step was wrong because it is against the law, against standard operating procedure, or against the national standard of "acceptable" tactical training. They will bring in experts to remind you that you were taught in a felony traffic stop class to use your car's loud speaker to hail a vehicle occupant. This tactic may not be applicable in your situation, but it will cloud the judge's or the jury's view.
Remember, the attorneys, experts, and media will have weeks to pore over actions you took in microseconds. And whether the standards, policies, or training they introduce in the court is your department's or not, the plaintiff's attorneys will find something to validate their stance and use it against you. This is one line of reasoning that does seem to have an effect on the jury; somewhere in this world what you did could have been wrong. Be prepared for such legal attacks, which will portray you as using poor tactics or making bad decisions. They will argue your poor tactics placed you in a position of danger, which had negative outcomes for their client. I do not like this argument, nor do I agree with it, but it's what the lawyers will do to you.