REUTERS
Volkswagen cars with bigger diesel engines also contained software devices designed to cheat in emissions tests, according to U.S. regulators, the BBC has reported.
Porsche, Audi and VW cars are all included in this new investigation, which affects at least 10,000 vehicles, the report reads.
The Environmental Protection Agency (EPA) said that cars with 3.0 liter engines from the years 2014 to 2016 were affected.
However VW denies the vehicles have software designed to cheat tests.
Instead the company says that cars with the 3.0 liter diesel V6 engines "had a software function which had not been adequately described in the application process."
Volkswagen said it was cooperating with the EPA to "clarify the matter."
"Volkswagen AG wishes to emphasize that no software has been installed in the 3-liter V6 diesel power units to alter emissions characteristics in a forbidden manner," the company said in a statement.
Meanwhile, Porsche said it was "surprised" by the EPA's allegations.
"Until this notice, all of our information was that the Porsche Cayenne diesel is fully compliant," it said in a statement.
The EPA says the investigation is ongoing.
In early September Volkswagen admitted to the EPA that cars from the model years 2009 to 2015 contained software designed to cheat emissions tests.
It said that 11 million cars were affected.
That prompted U.S. regulators to run further tests designed to detect such defeat devices and led to today's announcement from the EPA.