And the annual automotive unveiling showcases the evolution of more than glass and steel. The human models who accompany new-car displays at Cobo Center have done their share of changing with the times, as the new book Sirens of Chrome (Momentum Books, a division of Hour Media, $24.95) details. In her book, which was released last month, author Margery Krevsky takes readers through the transformation of auto-show models — from ball gowns and gleaming smiles to business suits and automotive expertise. Krevsky, the CEO and president of Production Plus, a talent and modeling agency with offices in Bingham Farms and Los Angeles, initiated the idea of auto-show models being trained as product-information specialists. As a result, today’s models have the face, the figure, and the facts. Krevsky’s 192-page book features rare photos of new wheels and the women who so radiantly promoted them throughout the decades.