US car sales tumbled by 23% in September as showrooms emptied after the government-funded boom from the 'cash for clunkers' programme, with General Motors and Chrysler hardest-hit.

Sales for General Motors and Chrysler - the two US car makers struggling to regain momentum after emerging from bankruptcy - dropped by 45% and 42%, respectively.

Ford - the only US car firm to have avoided bankruptcy - managed to hold its sales decline to 5% from a year earlier despite low inventories and reduced incentives for car shoppers.

Car makers had braced for a sharp pullback in September after the clunkers programme and taxpayer-funded credits of up to $4,500 drove sales sharply higher the month before.

In a reversal of fortune that underscores how deep the decline in US car sales has cut over the four-year-long slump, China's overall vehicle sales for September were almost twice as large as the industry-wide US tally, according to an estimate provided by GM.

Meanwhile, US sales for the three major Japanese automakers were also lower in September after gains in August during the short-lived cash-for-clunkers boom. Honda sales were down 20% in the month, while Toyota sales fell almost 13% and Nissan sales were down 7%.

Hyundai, which has taken market share through the US recession on a growing reputation for low-cost and high-quality vehicles, was the only big winner. Its sales jumped 27% in September. Combined with its affiliate Kia, Hyundai now ranks as the sixth-largest car maker in the US market, having outstripped Nissan over the first nine months of the year.

Major car makers held out hope for a gradual recovery in sales in the fourth quarter once dealer stocks of cars and trucks are built back up in the coming weeks and showroom traffic recovers from the slow pace of early September.

GM, which launched an ad blitz in September challenging consumers to compare its cars to rivals, remained the largest car maker by US market share at 21% compared with 17% for Toyota, now number two in the US.