BEIJING — For more than a decade, automakers around the world have been nervously awaiting the day when China would start exporting sizable numbers of cars to the West.


Now it seems they were worried about the wrong threat.


China is shipping just a few thousand cars a year to the European Union and virtually none to the United States. But China’s exports to emerging markets are surging as its own auto market slows and its automakers keep pouring billions into new factories. Roads in countries like Algeria, Brazil, Iran, Russia, Saudi Arabia and South Africa are increasingly dotted with cars from manufacturers like Geely, Great Wall Motors and Chery.


Less affluent buyers from Santiago to Baghdad are starting to buy cheap Chinese cars as alternatives to used cars, motorcycles and low-end models sold by multinationals. Chinese car exports were up 21 percent in the first five months of this year, and up 43 percent in May from a year ago.


The buyers are men and women like Jessica Gonzalez, a 43-year-old agronomist in Santiago, Chile. After owning several used cars, she wanted her next car to be new, but the more established models from Japanese, European and United States companies were out of her price range. Although her mechanic criticized the quality of Chinese cars, she ended up choosing a Chery S21 because it was roomy and well equipped.


“The price factor is fairly decisive,” Ms. Gonzalez said. “I paid $5,500 new and full. Toyota with similar features costs around $12,000.”


Chinese automakers said they were preparing for further expansion in exports to developing countries.


“They’re easy for us to operate in,” said Steven Wang, the deputy general manager for exports at Great Wall Motors Company. “In Europe, they have lots of laws for new entrants, and in Europe and the United States, customers like to keep familiar brands.”


The Chinese companies pose a potential challenge for the overseas divisions of companies like General Motors, Ford, Toyota, Volkswagen and Fiat, all of which are looking to emerging markets for growth and watching the Chinese contenders with varying levels of concern.


Annual auto sales in developing countries other than China have risen by 45 percent since 2005, to 21.3 million cars and light trucks last year, according to LMC Automotive, a global data company. Including China, emerging markets passed industrialized countries in 2010 for the first time in the number of cars and light trucks sold.


Since 2005, auto sales in industrialized countries have fallen 17.4 percent, to 36.2 million cars and light trucks last year.


The market in industrialized countries was still worth more than emerging markets, however, because sticker prices tend to be considerably higher. But with so much growth in developing countries, “you have to be incredibly aware of the domestic brands” emerging in China, said Michael Manley, the head of Chrysler’s international operations.


Western automakers have been buying a wide range of Chinese cars and then having engineers dismantle them to study the quality and likely cost of major components.


“We have a very thorough benchmarking process” to assess Chinese competitors, said Kumar Galhotra, Ford’s vice president for product development in Asia, the Pacific region and Africa.


So far, the quality of the best Chinese cars has been well short of their Western counterparts, leaving even many Chinese customers dissatisfied.


When J. D. Power & Associates, the consulting company, surveyed new-car buyers in China last year, it found that they reported 232 quality problems for every 100 Chinese-brand cars purchased. For cars carrying international brands, 131 defects were reported for every 100 cars.


Jacob N. George, the managing director of J. D. Power’s China division, said that Chinese automakers had been steadily closing the gap with their overseas rivals since his company began doing annual surveys in 2000. If trends continue, he predicted Chinese manufacturers would catch up in quality by 2018.


The shortcomings of Chinese cars tend to lie in basic designs. Chinese automakers spend an unusually low share of revenue on design, focusing on ruthless cost-cutting instead.


J. D. Power also surveys buyers in China on how appealing they find their cars after three months of use. Chinese brands consistently score worse than international ones, particularly in categories like engine noise, driving dynamics and seating comfort, Mr. George said.