GM, once an emblem of US post-war economic might, is being driven to the brink by dwindling sales that are expected to test cash reserves and the nerves of investors in the months ahead.

Crosstown rivals Ford Motor Co and privately held Chrysler LLC face similar pressures. As the automakers weigh their options to ride out the industry's most-trying slump in 25 years, thousands of Detroit families are doing the same.

For many, the choices line up from bad to worse. Last week, GM shares skidded to their lowest level since 1955. The stock had its worst week since trading in the wake of the September 11, 2001 attacks, with Wall Street analysts handicapping when and how it will raise new capital.

GM's sales have dropped 15 per cent so far this year, and its share of the US market is down to just 21 per cent. When major automakers report sales for June today, there is a chance that GM will be overtaken by Toyota Motor Co as the monthly sales leader, a reversal that points to the popularity of small cars like the Yaris and the abandonment of SUVs and trucks like the Yukon and Silverado.

GM has responded by slashing costs, cutting truck production and slashing its factory work force to less than half of the 118,000 it employed four years ago.

On a combined basis, GM, Ford and Chrysler have cut more than 100,000 factory jobs since sales began to slow in 2006.

For Detroit, the downturn has been brutal. Michigan's jobless rate jumped to a 16-year high of 8.5 per cent for May. Detroit led the nation with its home foreclosure rate last year.