In an effort to conserve cash, General Motors will require thousands of salaried workers to take two additional vacation days in December. Those days will be taken on top of GM’s two-week holiday shutdown next month.

The moves come after GM said Friday, November 7, that it was  battling “unprecedented economic and credit market turmoil’’ and warned that it might not have enough cash to operate by mid-2009.

GM ended the third quarter with $16.2 billion in cash on hand, down from $21 billion on June 30. The net quarterly loss was $2.5 billion, including one-time gains and charges. Before those special items, GM reported an adjusted loss of $4.2 billion. Revenue fell $5.8 billion, to $37.9 billion, and global unit deliveries dropped 11 percent.

GM is looking for an additional $5 billion in savings by the end of next year, on top of $15 billion earmarked in July.

In a letter sent November 5, all employees at GM’s Vehicle Engineering Center in suburban Detroit, the proving ground in Milford, Michigan, and the desert proving ground near Mesa, Arizona, were told that they would be required to take December 22-23 off, said GM spokesman Dan Flores.

Before the announcement, employees at those sites were scheduled to work those two days, and the holiday started December 24, Flores said.

“We notified the employees last week that in our continued efforts to conserve cash we are asking employees to take two additional vacation days,” Flores said. “It’ll give us significant savings in utilities and facility expenses.”

Employees who have taken all of their vacation time this year will be required to take the time off and will have two fewer vacation days next year, Flores said.

GM employs 16,000 to 17,000 workers at its engineering center, Flores said. He did not have the employee count at the two proving grounds.

He said world headquarters and manufacturing plants would remain staffed through December.

Filed by by Jamie LaReau of Automotive News, a sister publication of Workforce Management. To comment, e-mail editors@workforce com.

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