Henry Ford might be proud, but enviros are disappointed: William Clay Ford, Jr., great-grandson of the automobile pioneer, used to be known as the greenest person in the auto industry. But since taking the reins of Ford Motor Company last October, Ford has muted — and sometimes changed — his tune. The man who once jokingly called his company’s 19-foot-long Excursion the “Ford Valdez” has promoted sport utility vehicles and lobbied against increased fuel-efficiency standards. Still, the company says it will stand by pledges to improve SUV fuel economy, sell hybrid versions of the oversized vehicles, and redesign one of its plants to be more eco-friendly. Environmentalists, however, fear Ford is showing his true stripes and say that so far, the company’s record under his leadership is indistinguishable from those of other major automakers.