The poor figures come despite car-makers spending more on rebates, low-interest financing and other incentives in an effort to increase sales.

Ford last week reiterated assurances that it can survive the current economic downturn without resorting to government aid.

General Motors and Chrysler, the other two members of Detroit's 'big-three' vehicle manufacturers, have asked the US Treasury for another $21.6bn in loans on top of the $17.4bn approved in December.

US stocks closed down on Tuesday, with the Dow Jones Industrial Average falling 37.27 points, or 0.55 per cent, to end at 6,726.02 points, a day after the index hit its lowest close since 1997.

Economy fears

The US economy is struggling amid a global downturn and continuing turmoil in financial markets.

Obama said there was little hope for a short-term economic improvement [AFP]
On Tuesday, Barack Obama, the US president, said that he saw little hope of an improvement in the US economy in the near future.

"The economy's performance in the last quarter of 2008 was the worst in over 25 years. And frankly the first quarter of this year holds out little promise for better returns," he said.

Obama also praised Tuesday's launch of a new lending facility by the Federal Reserve, the US central bank.

The consumer lending initiative will generate up to $1trn in lending, US officials said.

"This will help unlock our credit markets, which is absolutely essential for economic recovery," Obama said, speaking two weeks after signing a $787bn stimulus package aimed at jolting the world's largest economy out of recession.

Officials testify

On Tuesday Ben Bernanke, the chairman of the Federal Reserve, told the Senate Budget Committee that he was not happy that AIG had been given a further $30bn in government loans, its fourth bailout by the US taxpayer.

"I share your anger," Bernanke said.

But he added that the government didn't really have a choice but to take the action because the collapse of AIG would have grave implications for the ailing US economy.

Bernanke and Tim Geithner, the US treasury secretary, and Peter Orszag, the Director of Office of Management and Budget, are testifying to US congressional committees on the state of the economy this week.