The price of precious metals used to make cars, platinum, palladium and rhodium, have plummeted in tandem with sales.

The slowdown in US car sales, which were 23 per cent lower last month than in September 2007, has been dramatic. This year, about 2m fewer light vehicles have been bought compared with 2007. Because platinum and palladium are crucial in the manufacture of autocatalysts, which reduce emissions, demand from carmakers accounted for about half of global consumption of both metals last year.