Fiberglass is heavy compared to some other forms of skin.
I believe Ken is not only looking at the shape of the object in regard to reducing drag, but also the drag across the surface. Some automotive roofs have longitudinal strips that channel the air, although they may have been placed primarily to protect the surface from cargo. Others, like large van roofs, have channels molded into the rooftop to create strength which also help air flow.
Sailboats found that creating a smooth surface in the hull so the water would flow easily wasn't as effective as waxing the surface so a layer of water stuck to it. The hull to water friction is greater than water to water friction, so the waxed surface moves with less resistance.
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