You will only improve your fuel economy by an almost immeasurable amount. A carbon fiber hood will cost about $600 and only weighs about 10 lbs less than the factory hood. It is not worth the money spent.A cold air intake and exhaust system will improve your fuel economy along with giving you more power because the car can breathe better, but again the money spent on the mods will not pay you back in fuel economy very much. Best thing you can do is keep your tires properly inflated, make sure your alignment is good, and that your air filter is clean.