Volkswagen's troubles just got a whole lot bigger.
Still reeling from the diesel emissions scandal, the German automaker said Tuesday it had set carbon dioxide emissions and fuel consumption figures too low when certifying some models.
It said about 800,000 mainly diesel vehicles were affected, and put a preliminary estimate of the cost to the company of the new admission at about two billion euros ($2.2 billion). It gave no further details about the vehicles.
Volkswagen (VLKAY) said it deeply regretted the new discovery, adding it would immediately begin discussing the consequences with relevant authorities.
"Volkswagen will endeavor to clarify the further course of action as quickly as possible and ensure the correct CO2 classification for the vehicles affected," the company said in a statement.
The safety of the vehicles was not compromised, it added.
Related: VW emission scandal threatens Porsche
The new irregularities came to light as part of an investigation into the installation of so-called "cheat devices" in as many as 11 million diesel vehicles worldwide.
Software in those cars kept emissions of nitrogen oxides many times lower in tests than on the road, allowing Volkswagen to meet clean air standards.
The diesel emissions scandal cost the CEO his job, and forced the group to set aside 6.7 billion euros ($7.4 billion) to cover recall costs. That resulted in a hefty third quarter loss. Analysts expecting that bill to rise significantly once the cost of legal action and compensation is included.
New CEO Matthias Mueller said he would stop at "nothing and nobody" to find out what had gone wrong at the company.
"This is a painful process, but it is our only alternative. For us, the only thing that counts is the truth. That is the basis for the fundamental realignment that Volkswagen needs," he said in a statement Tuesday.
Volkswagen shares, which have lost nearly a quarter of their value since the diesel scandal broke in September, fell 2% on Tuesday after U.S. regulators said some Porsche SUVs may have been rigged too.
Volkswagen disputed that claim. It says the "defeat devices" were installed in VW, Audi, Skoda and SEAT models.
But on Tuesday evening, Porsche said it would stop selling its Cayenne diesel vehicles, which were among those cited by U.S. regulators on Monday.
Porsche's statement said that it decided "in view of the unexpected U.S. EPA notice received yesterday, to voluntarily discontinue sales of model year 2014 through 2016 Porsche Cayenne Diesel vehicles until further notice. We are working intensively to resolve this matter as soon as possible."
