Chinese battery and automobile producer BYD Co. is scrambling to make a last-minute design change to its all-electric battery car and is now aiming to make the car available to private buyers in California and possibly a few other "key U.S. states" by 2012 after test marketing the car in Southern California during the second half of this year, said company Chairman and founder Wang Chuanfu in an interview.

The redesign of the car—called the e6—even before it is launched in the U.S. comes as a result of BYD's decision to improve the car's rear seating area and means the U.S. test marketing and launch of the electric car would be delayed, in the end, by about a year.

The company was aiming to begin the test marketing in California during the second half of last year. The e6 debuted in China last March as taxis in Shenzhen.

Though BYD is more known for its ambition in electric cars, the home-grown Chinese company sells mostly gasoline-fueled vehicles in China and is one of that country's top auto brands, with sales of more than 500,000 vehicles last year.

In the U.S., however, "Byd is going to be a new energy-car brand," Mr. Wang said in an interview on the sidelines of the Detroit auto show Monday. "That's because in the U.S. there is fierce competition for gasoline cars. I don't think we have an advantage, but with electric cars it's a different story."

Aside from the e6 all-electric car, Mr. Wang said BYD plans to make available to private U.S. buyers "over time" other electric-car models including the S6DM, a plug-in electric hybrid SUV, which BYD unveiled at the Detroit auto show Monday. The company has no plans to market gasoline-fueled cars in the U.S., he said.

The fate of BYD's battery car has a wider implication in China. It is widely seen as a litmus test for the global ambition of China's auto sector. China believes its relatively inexperienced auto makers, such as BYD, could use electric-vehicle technology to close the gap with more-established global car makers.

According to Stella Li, BYD's senior vice president who was put in charge of BYD's vehicle business in the U.S. last year, the Shenzhen company plans to ship as many as 50 e6 electric cars by the end of next year to fleet customers in Southern California, including the municipal government of Los Angeles. BYD last year began selling e6 cars to taxi operators in the southern Chinese city of Shenzhen. This test marketing would pave the road for BYD to make the e6 available for U.S. private buyers. BYD also plans to test its all-electric buses with the city of Los Angeles with an aim to supply electric buses for the city's public transit.

"We think California offers us the biggest opportunity for the e6 because the state is more enthusiastic about electric vehicles," Mr. Wang said.

BYD is currently redesigning the e6 to make it more comfortable, especially its rear-seat area that is currently cramped and sports an uncomfortable seat and an uneven, bumpy floor because of a beefy battery pack that needs to be stored under the seat.

At the auto show, BYD displayed a version of the redesigned e6, which Ms. Li described as "work in progress."

Ms. Li said she is aware of what she called "rumors" that the e6's launch in the U.S. is being delayed in part because of fear of potential intellectual-property infringement involving lithium powder—a critical raw material for lithium-ion batteries. Ms. Li denied the e6 U.S. launch delay has anything to do with such fears. "No, there is no worry at all," she said. "We have our own unique technology."