Woes of Big 3 U.S. automakers could eventually lead to exits from NASCAR

Imagine this: A Cup series involving competitors driving Toyotas, Hondas and Nissans.The thought of this induces nightmares and sends chills down the spines of many NASCAR fans, who love the sport in part because of its all-American history. The top three U.S. automakers -- GM, Ford and Chrysler -- have been the backbone of the sport we all love since it started. When Toyota began fielding cars