The American version of the scrappage scheme, dubbed 'cash for clunkers' will get an extra $2 billion (around 1.2 billion), but there's no more cash for the UK.
The US initiative will have its budget boosted after the original $1 billion was spent within days of the scheme's launch.
Shortages of stock at manufacturers, such as Chrysler, have confirmed the success of the scheme, and should result in the extra cash being approved by the US Senate within days.
No more cash for bangers in the UK
The UK's 300 million scrappage scheme has paid out 41 million since May.
The scheme is set to run until February 2010, or until funds have been used. However, there has been no indication that it will be given extra money.
A spokesman for the Society of Motor Manufacturers and Traders (SMMT) said: 'While we are pleased with the positive impact of the scrappage scheme on new vehicle sales, there is no indication that the UK budget will be extended.
'We urge motorists seeking a new car to buy now, before the money runs out.'