By TOM KRISHER and DEE-ANN DURBINDETROIT (AP) â¿¿ When the word reached the Orion Assembly Plant, it spread along the serpentine assembly line like news of a death or natural disaster: General Motors, the biggest automaker in the world, had filed for bankruptcy protection. On that grim day in 2009, Chevrolet and Pontiac sedans kept rolling down the line. And 1,700 worried workers stayed at their stations even as GM announced it would close the plant in a desperate bid to survive. "The unknown was the scariest part," recalled Gerald Lang, who had worked at Orion for two years installing dashboards and doors. "We really had no clue what was going to happen." There was something else that the workers didn't know: They were witnessing the opening act of one of the greatest recovery stories in American business. Nearly four years later, Chevrolets are still moving down the assembly line under the plant's 82-acre roof. Lang and his co-workers now build the Sonic, the best-selling subcompact car in the nation. It's a vehicle no one thought could be made profitably in the U.S., by a company that few people thought would last. But GM has not only survived, it has earned $16 billion in profits in the past three years. And the industry is on track to make this year its best year since 2007. Detroit's improbable comeback is the work of many: President George W. Bush, who authorized the first bailout loans; President Barack Obama, who made more loans; workers who took lower wages and focused more on quality to compete with foreign rivals; and executives and designers who developed better cars amid the financial maelstrom happening around them. To be sure, there were victims: shareholders, auto-parts makers and other suppliers who went out of business, as well as taxpayers who will never get all their money back.