Wow, I was thinking, "good post!" until I read all the responses. Obviously, I didn't think things through much like the rest of you. Of course, you're all correct about that shade being the least of the flying objects in a car should one be involved in an accident.

I suppose the lesson here is to (1) keep your car as free of debris/flotsam/jetsam as possible, (2) drive defensively, (3) buy a good carseat and learn how to properly install it in your car (hospitals and police/fire departments often have short classes/lessons on this.

But kudos anyway to the OP for taking the time to share a warning she learned by going to the hospital to learn how to properly install an infant car seat.