Carbon fiber is a great material. It can be used for structual members of a car, where fiberglass cannot. If you're building a car for competition, the weight savings can be significant. However, it is more expensive. Because carbon fiber is a bit exotic, having a clearcoated carbon fiber hood is a way to show off.
If you're going for fast, obviously lighter is better. But for most applications, the stock steel hood is just fine. It's a real amount of weight off the front end, but nothing you'd notice on the street.
