As long as cars have been for sales, alluring models have been used to entice buyers. Margery Krevsky's new book "
Sirens of Chrome: The Enduring Allure of Auto Show Models" looks at the history of both kinds of auto models. Some of them are literal "human hood ornaments," like this Marion Morgan Dancer showing off a 1927 Packard 343 Series Eight. Others may not climb on the hood -- but still play the role of ornament to the cars they are helping to sell.