Failing US carmaker General Motors says it will run out of cash this month unless the taxpayer comes up with $4 billion (£2.68 billion) immediately.

The latest plea of poverty comes as senior executives are ostentatiously displaying their penitence, shunning corporate jet travel and taking nominal salaries in a bid to sway politicians to their side.

GM, Ford and Chrysler were criticised for using corporate planes to get to Washington last month. GM chief Rick Wagoner says he will drive from Detroit to Washington in the company's hybrid petrol-electric vehicle the Malibu for this week's hearings.

Ford plans to sell five jets, and will pay chief executive Alan Mulally a $1 annual salary if the company gets a taxpayer handout. Wagoner and Chrysler chief Robert Nardelli will also get just $1 if a rescue plan is approved.

GM is seeking $12 billion in loans and a $6 billion credit line from a reluctant Congress. It will slash 34% of its workforce, close plants and reduce its product line-up.

"Our plan is part of an urgent request for federal funding to help the auto industry weather a major crisis," Wagoner said. He added that the request "demonstrates in detail why GM needs federal funding not just for the company, but to be beneficial to the US economy".

Ford has asked Congress for a credit line of as much as $9 billion, saying it expects to break even or be profitable before taxes in 2011. Detroit is seeking a total of $34 billion from taxpayers.

Legislators and the White House have been unwilling to approve a general bailout for the industry, saying it will have to make do with a previously approved $25 billion handout designed to retool the domestic industry to make more fuel-efficient vehicles.

Vehicle sales in the US plunged 37% in November to the lowest annual rate in 26 years as the recession kept buyers out of showrooms. That could work against the companies in their bid for rescue cash as congressmen say they will only help if they can see a long-term future for the carmakers.

"We hope that we can work something out" with the companies, Senate majority leader Harry Reid, a Nevada Democrat, said. "We don't want to throw them a lifeline if the lifeline doesn't get them to the shore."