Hasn't anyone thought of this yet? Iraq can't have many cars left by now anyway. They tend to explode alot over there. Every day a car here or there blows up and kills people and injures hordes of others. Here we are spending millions and billions searching and detaining people, and it turns out we can pretty much assume the bombs are in cars.
That much we know. Okay, Baghdad just try it. No cars for a while. It's not like the infrastrucure will suffer. Let's see what happens. Oh wait, then how are our "trusted" news media going to get around if we do that?