General Motors did not apologize for anything in its first trip to Congress more than two weeks ago to plead for a federal rescue. The company’s only problem, it insisted, was the current financial crisis.

“What exposes us to failure now is not our product lineup, or our business plan, or our long-term strategy,” Rick Wagoner, G.M.’s chief executive, said in his testimony.

On its return visit to a skeptical Congress this week, however, General Motors bowed its head. “G.M. has made mistakes in the past,” Mr. Wagoner told Congress, and named three: agreeing to expensive union contracts, not investing enough in smaller cars and failing to convert its plants so they could build more than one type of vehicle.

It was an unusual concession from a company that has rarely felt the need to apologize for anything, given its bragging rights as the world’s largest automaker with operations in 35 countries, and as a company that has built 445 million vehicles and sat atop corporate America for much of its 100-year history.