I think three scenarios that would be better for the CCWer to try would be 1) firing at a moving vehicle while standing still, 2) firing at a moving vehicle while moving for cover and 3) firing at a moving vehicle while in a moving vehicle.
There was a story in the recent issue of Combat Handguns where a guy tried to pass another car on the road. The other car wouldn't let him pass and wouldn't let him move back into the right lane when there was on-comming traffic. He pulled out a 1911 Commander from his glove box and convinced the other driver to leave him alone. While he didn't have to fire a shot, he very well could have had to.
Sometimes you also get some whole "A" on your bumper. If they tried to run you off the road, could you send some lead through the back window while keeping your car on the road? I've never had to shoot while driving but it is something I've thought about because I know that my car is not the fastest thing on the road. I can't afford a Koenigsegg! :P
http://www.youtube.com/watch?v=3CRzXoWTka8