Toyota's (NYSE: TM) net grew 7.5% in the last quarter, but it indicated that it may not be quite so fortunate in the current period.

According to Reuters, the improvement was due to "speedy sales growth in China, Russia and other emerging markets." The big car company said it was still worried about the US economy.

The figures from the Japanese company show the difficulties that all of the global automotive firms face now. They are seeing double-digit sales increases in emerging markets, but in their largest market, the US, sales could be extremely poor this year.

Even that analysis masks the real long-term threat to Toyota's growth. In most emerging markets, there are already large automotive firms. Those include Shanghai Automotive in China and Tata Motors (NYSE: TTM) in India. These companies are not going to let big overseas operators simply come into their countries and take large pieces of the market.

The US economy may be the short-term enemy to Toyota, but competition in emerging markets is likely to be its challenge for the next decade.

Douglas A. McIntyre is an editor at 247wallst.com.