Car makers in the US have reported a slowdown in domestic sales in June, as Asian manufacturers continue to make significant gains in the US market.

Both GM and Ford posted double digit declines as sales incentives, which are now key to driving demand, dried up.

According to BBC News Online, GM experienced a sales decrease of 15.5 per cent in June year-on-year, while Ford sales were down 11.2 per cent.

However, Toyota increased sales in the US by 5.9 per cent, to secure an 11.9 per cent overall market share.

Meanwhile, Nissan sales jumped by nine per cent and Hyundai increased sales by 20.1 per cent.

Commenting on the drop in sales, Lehman Brothers' automotive analyst Joe Phillippi, stated: "There's no question that there's some payback from the really aggressive incentive programme. As the result of ever more aggressive incentives... sooner or later you reach some levels of saturation."

Changes in vehicle production levels are likely to affect the amount of platinum and palladium purchased by the auto industry, which uses it in autocatalysts to control harmful emissions.