China has been the world's largest auto market for several years now, with 18 million passenger cars and another 4 million commercial vehicles sold there last year.

But until recently, sales of plug-in electric cars have lagged those in the U.S. (whose market seems likely to be around 17 million vehicles this year).

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Now, according to an article on the Chinese news site Sina Auto (via Want China Times), in September the country's electric-car sales exceeded those of the U.S.--likely for the first time.

While U.S. plug-in sales vary from month to month, as do vehicle sales overall, this year's rate is roughly 10,000 electric cars a month on average.

BYD Qin plug-in hybrid in showroom in Costa Rica

BYD Qin plug-in hybrid in showroom in Costa Rica

In September, according to the article, Chinese buyers purchased 11,991 cars with plugs throughout the country, against 10,551 in the U.S.

ALSO SEE: China's Electric-Car Future: Government Subsidies, Buyer Resistance

Some of those Chinese electric cars would likely be deemed low-speed vehicles under U.S. law, and many would not pass North American crash-safety tests.

Still, given the hurdles to electric-car adoption in the country--including fierce price competition for lower-priced cars, and the prevalence of large apartment buildings against single-family homes--the total is a notable achievement.

Chinese battery electric crossover: BYD e6 test drive, Los Angeles, May 2012

Chinese battery electric crossover: BYD e6 test drive, Los Angeles, May 2012

Both national and regional governments in China are heavily pushing adoption of electric cars as one way to address the dangerous level of airborne emissions from vehicles and industry in most Chinese cities.

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So-called "new energy vehicles" are increasingly mandated by government bodies for public fleets and public transportation, including a growing fleet of electric buses.

The definition of a new energy vehicle can vary from jurisdiction to jurisdiction, but in general it means a car that plugs in--whether battery-electric cars like the Kandi or plug-in hybrids like the BYD Qin.

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