Worst of times, best of times in Detroit: Wagoner out, fuel efficiency in

It's a down day, but in a sense it's an up day for the U.S. auto sector, since recent developments may mark the beginning of new period of recovery and growth.

Of course, news that General Motors (GM) C.E.O. Rick Wagoner had resigned following a request from the Obama administration as a precondition to additional U.S. government aid, would be hard to interpret as a good data point for the U.S. auto sector. It is a painful, but necessary step, many auto industry analysts agree.