A polymeric engine hood assembly (100, 101, 103, 104, 105) for use in a vehicle, comprising: an exterior panel (12, 52, 62) having an exterior panel engine facing surface and an exterior panel outermost surface, wherein the exterior panel extends in an x direction; a fender skin (11, 51, 61) adjacent to a portion of the exterior panel engine facing surface at a junction surface, wherein the fender skin (11, 51, 61) has a fender skin engine facing surface and a fonder skin outermost surface, wherein a portion of the fender skin (11, 51, 61) extends in the x direction and wherein a portion of the fender skin (11, 51, 61) extends in a y direction; characterised by: a reinforcing structure (53, 63) including a body comprising a reinforcing structure first surface and a reinforcing structure second surface, wherein the reinforcing structure (53, 63) includes alternating ridges and flanges extending along the reinforcing structure (53, 63) in the y direction forming corrugations, wherein the corrugations extend at least partially transversely across the body of the reinforcing structure (53, 63); wherein indentations are disposed in the corrugation flanges on the reinforcing structure (53, 63) and wherein the reinforcing structure (53, 63) is adjacent to and extends along a portion of an exterior panel engine facing surface and along a portion of a fender skin engine facing surface; wherein the reinforcing structure (53, 63) includes a connecting ridge extending transversely across the reinforcing structure (53, 63) located between indentations, wherein the connecting ridge is configured to accept the junction surface of the exterior panel and the fender skin (11, 61); wherein channels are formed in air cavities located between the ridges on the reinforcing structure (53, 63) and the engine facing surfaces (23, 27) of the exterior panel and the fender skin. an exterior panel (12, 52, 62) having an exterior panel engine facing surface and an exterior panel outermost surface, wherein the exterior panel extends in an x direction; a fender skin (11, 51, 61) adjacent to a portion of the exterior panel engine facing surface at a junction surface, wherein the fender skin (11, 51, 61) has a fender skin engine facing surface and a fonder skin outermost surface, wherein a portion of the fender skin (11, 51, 61) extends in the x direction and wherein a portion of the fender skin (11, 51, 61) extends in a y direction; characterised by: a reinforcing structure (53, 63) including a body comprising a reinforcing structure first surface and a reinforcing structure second surface, wherein the reinforcing structure (53, 63) includes alternating ridges and flanges extending along the reinforcing structure (53, 63) in the y direction forming corrugations, wherein the corrugations extend at least partially transversely across the body of the reinforcing structure (53, 63); wherein indentations are disposed in the corrugation flanges on the reinforcing structure (53, 63) and wherein the reinforcing structure (53, 63) is adjacent to and extends along a portion of an exterior panel engine facing surface and along a portion of a fender skin engine facing surface; wherein the reinforcing structure (53, 63) includes a connecting ridge extending transversely across the reinforcing structure (53, 63) located between indentations, wherein the connecting ridge is configured to accept the junction surface of the exterior panel and the fender skin (11, 61); wherein channels are formed in air cavities located between the ridges on the reinforcing structure (53, 63) and the engine facing surfaces (23, 27) of the exterior panel and the fender skin. a reinforcing structure (53, 63) including a body comprising a reinforcing structure first surface and a reinforcing structure second surface, wherein the reinforcing structure (53, 63) includes alternating ridges and flanges extending along the reinforcing structure (53, 63) in the y direction forming corrugations, wherein the corrugations extend at least partially transversely across the body of the reinforcing structure (53, 63); wherein indentations are disposed in the corrugation flanges on the reinforcing structure (53, 63) and wherein the reinforcing structure (53, 63) is adjacent to and extends along a portion of an exterior panel engine facing surface and along a portion of a fender skin engine facing surface; wherein the reinforcing structure (53, 63) includes a connecting ridge extending transversely across the reinforcing structure (53, 63) located between indentations, wherein the connecting ridge is configured to accept the junction surface of the exterior panel and the fender skin (11, 61); wherein channels are formed in air cavities located between the ridges on the reinforcing structure (53, 63) and the engine facing surfaces (23, 27) of the exterior panel and the fender skin.