The U.S. may still be the world’s biggest car market but its sales are on the decline, making it much harder for struggling carmakers as all brands are now competing in a shrinking market. The poor state of the market saw Ford lose more retail share (not including fleet sales) last year than any other carmaker, its market share dropping from 15.1% at the end of 2006 to just 14.2% at the end of last year.

This may not sound like a lot but a 0.9% decline in market share equates to roughly half of the production output at one of Ford's plants, reports the Free Press. The latest result was better than the previous year where Ford lost nearly two full percentage points of retail market share but there doesn’t seem to be any turnaround in sight.

Japanese rivals have picked up most of Ford's decline in the U.S. market, while GM’s sales have managed to stabilize at about 22% of the market. The results show that U.S. automakers commanded less than half of the local market for the second time in a row last year with just 47.1% of the market, down from 48.4% in ’06.

Ford is blaming the economy but it’s a poor argument considering rivals are gaining market share. However, the slide is slowing. In the fourth quarter, for instance, Ford lost only 0.1% market share, and several major model updates in the pipeline should generate more sales in coming years.