But the rates of growth in these mature markets are modest at best, and in the case of Japan, even on the decline. Detroit enjoys high market penetration in Australia, where Big Three brands combine for 26 percent of car sales. But the Australian market, at 845,000 units annually, is relatively small and already near saturation. Besides that, Big Three brands have been losing share in Australia over the years to competing Japanese brands. Meanwhile, car sales in Japan and Korea are on track to reach a combined 5.3 million units this year. Of this total, Ford, GM and Chrysler brands will account for a roughly 205,000 units, or about 3.8 percent of the market. And this figure includes sales of 155,000 Daewoo brand vehicles, GM's Korean subsidiary. While it can be argued that structural and cultural hurdles impede Detroit automakers' growth in Japan and Korea, it seems that Detroit automakers have all but abandoned hopes of competing in these markets. Small and Expanding MarketsThe Small and Expanding markets consist of the collection of countries in Southeast Asia -- led by Thailand, Indonesia, Malaysia, and the Philippines -- plus India. Car sales in Southeast Asia, known as ASEAN, will reach 1.6 million units this year. Detroit's share will amount to about 55,000 cars and pickup trucks, or 3.5 percent of the total. And the bulk of these sales will be isolated in one country -- Thailand. Ford, GM and Chrysler invested more than $800 million into Thailand in the 1990s, hoping to secure a strong position in ASEAN's most important market. But the Japanese, led by Toyota and Honda, have largely repelled Detroit's advance. Japanese vehicles today account for 92 percent of total Thai sales. Car sales in India will reach 1.5 million units in 2008, and progress by Detroit automakers has been moderate. Combined Big Three sales will climb to about 96,000 units this year, or 6 percent of the market. It is tough for American makes to compete in India's highly prices-sensitive market, where the likes of Tata declare plans for producing and selling $3,000 cars. Again, Japanese automakers account for the bulk of sales, roughly seven out of every 10 of every ten cars sold in the region. Large and Expanding MarketFinally we turn to Asia's Large and Expanding market, China. It is here that we see Detroit has focused most of its attention. China will sell some 6 million cars in 2008, and U.S. automakers will account for about 12 percent of the total, or 720,000 units. Given that 51 brands are now produced and sold in China -- in addition to another 15-20 import brands -- Detroit's performance thus far is commendable. But current success is no guarantee of future achievement. Beijing Jeep, which entered China in the early 1980s as the first foreign automotive joint-venture, no longer exists, a casualty of partner conflicts and ill-timed products for the market. Chrysler is undergoing a complete management overhaul and now relies on licensing agreements and imports -- not joint ventures -- to sell Dodges, Chryslers and Jeeps into the market. Sales of Chrysler-brand vehicles in China this year will reach about 20,000 units. Ford will sell nearly 190,000 vehicles in China this year, and the brand is gaining positive recognition among Chinese consumers. The compact Focus is on track to sell some 125,000 units this year, while the midsize Mondeo should approach 40,000 units. But as the China market softened over the summer, Ford's momentum has slowed as well. General Motors will sell some 510,000 vehicles in China in 2008, and has consistently grown volumes since it entered the market in the late 1990s. But GM's share of the China market peaked at 11 percent in 2005, and today has fallen back to 8 percent. Moreover, Toyota has quietly replaced GM as the second largest vehicle manufacturer in China in 2008 (behind Volkswagen), while sales of the once highly popular Buick brand have flattened. China's current size and future potential is highly attractive, and Detroit automakers are right to make it a priority. But they shouldn't neglect other markets in the region, for several reasons. First, Asian markets ex-China still account for more than 9 million vehicle sales annually; that's a lot of potential business Second, China is a brutally competitive market in which margins are shrinking every month. Third, should Chinese sales continue to weaken in the coming months, it will be vital for Detroit to have a second source of growth to which it can turn. Autos Insider columnist Michael J. Dunne is Managing Director -- China for J.D. Power and Associates.