(FORTUNE Magazine) – Affable and engaging in private, Wagoner, 50, is Detroit's new tough guy. His message to competitors whose customers are fleeing to foreign makes: "Stop whining." If $4,000 worth of incentives on GM cars pushes less-efficient automakers to the brink, Wagoner doesn't care: He's going to do what makes sense for his company. Despite GM's size, Wagoner is hemmed in by union contracts, government regulations, and giant health-care and retiree costs. And he hasn't yet succeeded in getting GM's stock price to stay up: Even though it ranks second in revenues, GM is just No. 94 in market capitalization. Still, Wagoner has more clout than any American in the industry. --A.T. III