What about accident/impact resistance? And before anyone screams that Kevalr Carbon Fiber is....
stronger than steel, yes, it is, but it has to be wrapped,formed and vaccuum packed in an auto clave to have serious structural regidity. This will not happen with a carbon fiber trunck lid that wouldn't cost around 1/3 the price of an S4. Ever hear how the front wing on a CART or IRL car costs $12,000-$25,000?
Someone could make a CF decklid for probably $400-$700, but it would not be strong enough, safety wise, for me to use it.
Mike S