"Employees have indicated in an internal investigation that there were irregularities in ascertaining fuel-consumption data," a Volkswagen representative says.
U.S. authorities reportedly seized a Volkswagen employee's passport during a recent trip, stoking fears about criminal prosecution.
German regulators stepped up their scrutiny after Volkswagen admitted to false carbon-dioxide emission data concerning about 800,000 cars sold in Europe.
The carmaker says 800,000 cars could be affected in the latest issue involving "irregularities" in carbon dioxide emissions data, and cost the company $2.2 billion.
The U.S. Environmental Protection Agency said Monday that certain Audi, Porsche and Volkswagen models with 3.0 liter engines were also rigged to pass pollution tests.
The scandal's fallout continues: Affected models include the 2014 VW Touareg, the 2015 Porsche Cayenne and the 2016 Audi A6 Quattro, A7 Quattro, A8, A8L and Q5.
Researchers cautioned driverless cars still have a long way to go before full safety ramifications are understood.
Nearly 700,000 cars in Spain have been affected by the Volkswagen group's trickery.
CEO Matthias Mueller will look to quell investor fears after the scandal-hit automaker announced a $3.85 billion loss in the third quarter.
The auto industry has said, in effect, that drivers own the steel in their cars, but not the software. But the U.S. government has ruled differently.
The Violation Tracker database, compiled by think tank Good Jobs First, tracks companies that have violated U.S. environmental, health and safety laws.
“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.