FRANKFURT (Reuters) - Volkswagen VOWG_p.DE needs to do more to investigate how Europe's largest carmaker became embroiled in emissions cheating, shareholder Union Asset Management said on Wednesday.

The logo of German carmaker Volkswagen is seen on a wheel at a showroom of Swiss car importer AMAG in Duebendorf, Switzerland February 12, 2016. REUTERS/Arnd Wiegmann

“Are we content with the crisis management at VW? No, not at all,” Union Asset Management’s Chief Investment Officer and executive board member Jens Wilhelm said, citing a lack of transparency and the way VW was investigating the scandal.

“Volkswagen needs more independence on the supervisory board to win back trust with investors,” Wilhelm added, without elaborating.

Reuters data showed Union held a 0.18 percent stake in VW, worth about $42 million, at the end of September last year.

VW’s supervisory board, its board of directors, includes long-term veterans close to management, such as labour representatives, members of the controlling Porsche and Piech families and representatives from shareholder Lower Saxony.

“Dieselgate” erupted in September after U.S. and California environmental regulators said they were investigating whether VW had deliberately circumvented clean air rules on diesel cars by using software to cheat emissions tests.

Just before this, Volkswagen said it would promote Chief Financial Officer Hans Dieter Poetsch to the supervisory board, a role he took on in early October.

Poetsch said in December only a small group of employees were responsible for manipulating U.S. diesel emissions tests, adding there was no indication that management board members had been involved.

Since then, a media report alleged that a high-ranking employee warned senior VW managers about the U.S. probe in May 2014, raising questions about how much senior managers knew.

Poetsch was chosen as chairman because he is seen as a relatively neutral and unthreatening figure within VW, where radical reforms can be blocked by labour representatives who hold half the supervisory board seats, and its home state of Lower Saxony, which holds a 20 percent stake.

VW has admitted installing illegal software to conceal that U.S. diesel vehicles, of which 580,000 have been sold since 2009, emit up to 40 times allowable emissions.

U.S. owners of vehicles with higher-than-stated emissions are expected to seek billions of dollars in damages, while the U.S. Justice Department has sued VW for up to $46 billion under the Clean Air Act.

Volkswagen has postponed its financial results for 2015 and delayed its annual shareholders’ meeting as it struggles to put an exact price on the scandal.