WASHINGTON, DC: September 09, 2016. A Volkswagen (VW) engineer has pleaded guilty for his role in implementing software designed to defraud U.S. regulators and customers beginning in 2006.

James Liang's plea agreement with the U.S. Department of Justice (DoJ) is based on his cooperation with its ongoing investigation.

Between 1983 and 2008 Liang worked in VW's diesel development department in Wolfsburg, Germany.

In 2006 he was part of a group that started to design a new 'EA 189' diesel engine for sale in the U.S. When they realized they couldn't meet stricter government emissions standards, they designed and implemented software to cheat the emissions tests.

According to the plea agreement, employees of VW and its U.S. subsidiary met subsequently with the Environmental Protection Agency (EPA) and the California Air Resources Board to seek vehicle certification. Liang admitted that during these meetings his colleagues misrepresented VW compliance and hid the existence of the defeat device.

As part of the certification process for each new model year between 2009 and 2016, VW employees continued to claim the diesel vehicles complied with the U.S. Clean Air Act - despite the results of an independent study that showed car emissions were up to 40 times higher on the road than shown during testing.

The announcement coincides with the publication of the latest Dow Jones Sustainability Index that lists BMW as the most sustainable car company in its sector.

Produced in conjunction with RobecoSAM, a Swiss investment specialist focused exclusively on Sustainability, the index is based on the analysis of 3,400 leading companies and responses from 867.

"With 2016 likely to be the hottest year on record, investors are again reminded that companies' environmental and sustainability efforts are crucial to their financial outcomes," observed David Blitzer, S&P Dow Jones Indices managing director.

Based on the results from its 100-strong questionnaire, RobecoSAM concluded that the surveyed companies scored lowest on "operational eco-efficiency" and human capital development.

"Surprisingly, many companies still underestimate the importance of human capital development and lack the ability to not only qualitatively, but also quantitatively, link investments in human capital with tangible business benefits," the report observed.

According to the DoJ, Liang admitted that from 2009 VW marketed its diesel vehicles to U.S. consumers as "clean diesel" and environmentally friendly, despite knowing the representations were false.

Last year VW admitted cheating on the emissions tests of nearly 500,000 diesel vehicles in the U.S and subsequently nearly 11 million worldwide. In July this year it settled a U.S. consumer class action lawsuit for US$15 billion.

The DoJ said the FBI and EPA continue to investigate VW.