The Alpha N vented bonnet for the BMW G8X M3 and M4 is made entirely of carbon fiber with an additional layer Kevlar on the inside, which serves the stability.
Taking some queues from the M4 GT3 race car, this vented carbon bonnet weighs 40% less than the original. While BMW utilized aluminum to keep the factory bonnet as light as reasonably possible for a production car, the Alpha N bonnet comes in at only 17lbs vs the 28lbs of the OE hood.
NOTE: Vent mesh not included.