China's electric car manufacturers are introducing trade-in plans for new energy vehicles, a move industry insiders say will stimulate the booming sector in the world's largest auto market.

BYD is working on a trade-in plan that could be unveiled as early as 2017.

"The plan will be drafted in accordance with national regulations to meet the customer demand (for trading used cars)," says Zhao Changjiang, head of the company's Beijing and Tianjin sales division. He declined to offer more details.

BYD's new energy vehicles are among the most popular in China, accounting for 30 percent of the market in the first quarter this year.

BJEV, the new energy vehicle arm of BAIC Group, is also drawing up a trade-in plan, according to a report by Beijing Business Today.

"We have been conducting studies in the field of used new energy cars for several years, and our plan will be made public by the end of the year," Zhang Yong, general manager of BJEV's sales division, was quoted as saying.

China is the world's largest market for new energy vehicles, with 207,000 units sold in the first seven months of the year, including pure electric models and plug-in hybrids, according to the China Association of Automobile Manufacturers.

However, the country still lacks a system for evaluating and trading in used cars.

Experts suggest the situation is the result of there being few new energy vehicles in the market - they accounted for about 1 percent of total car sales at the end of 2015 - and that their evaluation demands more professional expertise than gas-powered cars.

Yet many believe the carmakers' trade-in pl ans will be an industry model that helps speed up the development of a system of evaluation and trading of used cars, as well as also stimulating new car sales.

Ma Lianhua, a dealer in new energy vehicles in Beijing's Tongzhou district, says one of the concerns of potential customers is how to deal with the battery when its warranty expires.

According to a notice released by four ministries in May last year, carmakers may be required to offer warranties that cover batteries and electric motor systems for the first eight years or 120,000 kilometers.

"If they put in place such a plan, they leave customers with no worries, and surely it will boost sales," says Ma, who adds that he now sells about 30 new energy vehicles a month.

Experts have also called for national standards for the recycling and disposal of batteries to be established as soon as possible.

According to the China Automotive Technology and Research Center, there will be 120,000 to 170,000 metric tons of used batteries in the country by 2020 based on China's plan to have 5 million e-cars on the roads by then.

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