(Yicai Global) May 29 -- BYD has developed the technology to control emissions from atmospheric fuel tanks and this complies with China’s rules and standards for evaporative emissions, the Chinese new energy vehicle giant said today as the fallout with Great Wall Motors over car emission tests rumbles on.

The tech enables BYD's cars to finish fuel steam desorption, power generation and engine maintenance without increasing fuel consumption and noise, the Shenzhen-based carmaker said on the China Info website, in response to a question from an investor. This is fair and reasonable and is in conformance with the law, it added.

BYD has released a patented solution which reduces the need for pressure-oil tanks, but without taking the cars apart it is not possible to prove if BYD is actually commercializing this patent, a power assembly engineer at a car firm told Yicai Global.

Shares in BYD and Great Wall Motors have tumbled for three straight trading days since the spat first broke out when Great Wall Motors alleged that two of BYD’s electric cars do not meet vehicle emission standards on May 25.

BYD’s Shenzhen-traded shares [SHE:002594] were trading down 1.1 percent at CNY244.12 (USD34.55) as of 1.15 p.m. China time today. Great Wall Motor’s stock price [SHA:601633] sank 3.7 percent to trade at CNY22.85.

BYD’s Qin Plus DM-i and Song Plus DM-i models use normal-pressure fuel tanks and therefore purportedly fail to meet the country’s vehicle emissions standards, Great Wall Motors said May 25, citing the filing it made to the Ministry of Ecology and Environment, State Administration for Market Regulation and the Ministry of Industry and Information Technology on April 11.

BYD retorted that it reserves the right to carry out legal action of its own and is firmly against any form of unfair competition. All of the Shenzhen-based company’s autos conform with national standards and they have all passed verification by the country’s authorities.

Great Wall Motor bought the two cars and sent them to the China Automotive Technology & Research Center for testing, BYD said. They were not tested according to national-level standards, it said.

Tests should be organized by a third party and testing can only be done on cars that have a mileage of at least 3,000 kilometers. However, the two vehicles that were sent in by Great Wall Motors had only driven between 450 km and 670 km each. Therefore, BYD regards the test results as invalid and Great Wall Motor cannot use them against BYD.

Atmospheric fuel tanks costs between CNY500 (USD71) and CNY1,000 less than pressure-oil tanks and ordinary tanks do not meet China's VI emission standards, the engineer said.

Editor: Kim Taylor