“VW may be facing sales difficulties due to the [diesel emissions] scandal toward next year in Europe and the U.S.," one analyst said.
A letter noted the “significant discrepancy between the certified emissions and those actually observed on the road.”
A Volkswagen representative confirmed CEO Matthias Mueller would accompany German Chancellor Angela Merkel on her trip to China.
The automaker anticipates the costs of the scandal might exceed 30 billion euros ($33 billion), according to a German monthly magazine.
The German company also plans to re-use as many parts as possible in the next generation of its popular Golf model to save hundreds of millions of euros.
The German automaker admitted last month that nearly 11 million vehicles globally may have been equipped with the cheat software.
Porsche's 2008 market manipulation case has been eclipsed by majority shareholder Volkswagen's ongoing legal troubles.
The German state of Lower Saxony, which filed the complaint, is reportedly a minority shareholder and its governor is on the automaker’s supervisory board.
Authorities with France's environmental-protection agency assisted in conducting a search of the headquarters of VW's French unit.
Some automobile-industry experts say the existence of several versions of the defeat device raises the possibility that a range of employees were involved in the deception on emissions tests.
Several German media outlets have reported that Martin Winterkorn, who quit at VW last month, would step down from his remaining posts related to the company in coming days.
The Volkswagen Group accounted for 23.3 percent of the European Union's auto sales in September — its lowest level in six months.
In the wake of the Volkswagen scandal, Germany's environment minister wants to eliminate tax breaks for diesel cars, while France will jack up diesel prices.
A total of 11 million of Volkswagen's diesel vehicles have been affected by the worst crisis in the company's 78-year history.
The German automaker, facing repercussions from its diesel emissions controversy, is now touting the electric VW Phaeton, a challenger to the Tesla Model S.
Volkswagen’s recently announced new North America boss changed his mind and quit the company.
The German carmaker, reeling under the biggest crisis in its 78-year history, also announced plans to develop hybrids and electric cars and accelerate its "efficiency programs."
The German automaker's emissions-software controversy has affected mostly European nations, but countries in Africa and Asia have not been immune.
The recall in the company's largest market came amid reports that a European lender may freeze funds to the carmaker.
Martin Winterkorn, the VW CEO who steared Europe's largest carmaker to crisis, has since resigned, and upstarts in the corporation are calling for change.
Four other carmakers were not accused of installing any software to cheat on the emissions tests, but their diesels spew more pollution than shown in tests.
Meanwhile, Volkswagen's Australia unit said it will conduct a voluntary recall of nearly 100,000 vehicles equipped with emissions-rigging software.