While major automakers like GM and Toyota are preparing to build their first plug-in hybrid vehicles, a Chinese battery maker has beat them to it.

As of yesterday, Shenzen-based BYD Auto–a subsidiary of leading Chinese rechargeable-battery producer BYD Group–is selling the world’s first mass-produced plug-in hybrid car, according to Bloomberg. This battery-loaded version of BYD’s F3 sedan is said to travel up to 100 kilometers (62 miles) on stored grid power alone.

Many observers deride the car’s styling as plain and derivative. But the BBC’s global business correspondent Peter Day, who drove BYD’s plug-in this weekend, says that they’re missing the point: “Critics say this is a copycat car, but that is how the Japanese auto industry started.”

Green Car Congress reports that the plug-in is dubbed the F3DM after its “dual-mode” hybrid system–misleadingly dubbed, that is, because the vehicle actually operates in three distinct modes:

• a battery-powered EV mode
• a series-hybrid mode whereby the gas engine recharges the batteries while the electric motors drive the wheels, and
• a parallel-hybrid mode whereby both motor and engine drive the wheels.

This marks a contrast with GM’s Chevy Volt, due out two years from now, which dispatches with the parallel hybrid option.

BYD Auto’s parent company is making lithium batteries for the car using lithium iron phosphate cathodes–a safer design than the lithium cobalt oxide cathodes used in cell-phone batteries. Boston-area battery developer A123 uses the same chemistry, and although A123 is thought to have lost out in the competition to supply the first-generation Chevy Volt, it is in the running for many other hybrids and electric vehicles in development.

BYD says that it will bring the F3DM to the U.S. market in 2011, but it must first pass U.S. crash tests and set up a dealer network. The company has a well-connected U.S. investor to help navigate the U.S. hurdles: billionaire investor Warren Buffet, whose Berkshire Hathaway investment group bought a one-tenth stake in BYD for $230 million in September.

So China has beat the U.S. and Europe to market with what was supposed to be GM’s signature development. The headline reinforces a growing sense that China is suddenly a green-technology developer to be reckoned with. It looks as though the Cleantech Group may have got it right earlier this month when, summing up its forum in Shanghai, it concluded that China could soon be “the world’s leading laboratory, market for and exporter of clean technologies.”