A few other bad things that can happen when you shoot at cars include: hitting a passenger, hitting an innocent bystander, causing an out-of-control car to slam into a crowd of innocent bystanders, and, since handguns weren't made to shoot windshield glass, your round may ricochet and go God knows where. All of these bad outcomes could put you in a legal jackpot.
But let's say everything goes the way you wanted it to when you chose to fire on the driver of an oncoming car. Your shots find the mark. The driver is killed, and the car is stopped with no further injury to you or innocent bystanders. Even if your shooting was in policy with your agency, you are still likely in big trouble.
Remember, we're not talking about a case of a bad guy throwing shots at you from a car and you having to return fire. We're talking about shooting an otherwise "unarmed" driver who may or may not have been intending to run you down. Your local papers will hammer you with the fact that the driver was "unarmed." So will his or her attorney.
Worse, reflexes and physics being what they are, you will likely jump out of the way of the oncoming vehicle as you shoot and continue firing as it passes. Which means that when you fired the fatal shot, the threat to your life had ended.
And that's a real problem, says John Makholm, a veteran police officer and trainer who is also an attorney with Florida-based Peter M. Walsh & Associates. "We had a case in Gainesville, Fla.," Makholm says. "The officer was standing in front of the perpetrator's car, and the perp drove at him, and he shot the car coming toward him and going past him. If you are shooting at a car that's coming toward you, then I think it's a natural inclination to keep shooting as it passes you and after it passes you. The problem is, as it passes you, all things being equal, it's no longer a threat to you. After it has passed you and is going away from you, it's certainly no threat to you. You no longer have a reason to be shooting."