A couple of years ago, General Motors Corp. ( GM ) finally seemed to be getting its act together. Profits were strong and the company had recorded back-to-back annual gains in auto market share -- something that had not happened since the 1970s. Cadillac and Hummer were genuine hits -- and, more important, big moneymakers. Former Chrysler Group ( DCX ) star Robert A. Lutz was leading a renaissance in styling, stealing the spotlight at auto shows. But today, despite billions invested in new cars, GM is once again losing ground. And suddenly its slide seems to be picking up speed. That point was driven home on Jan. 13, when Chairman and Chief Executive G. Richard Wagoner Jr. announced that he was moving to wall off his most reliable profit machine -- the mortgage-lending portion of General Motors Acceptance Co. ( GM ) -- bowing to the real possibility that his flailing auto business will be downgraded to junk status.