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The 2015 Porsche Cayenne diesel was cited by the EPA (Photo: Porsche)

Volkswagen, in response to new allegations of illegal software deployment, denied that vehicles with V6 TDI engines sold in the US are equipped with programs that can detect emissions testing cycles and react to them.

The US Environmental Protection Agency (EPA) issued a so-called "notice of violation" November 2 that said it had "determined that VW manufactured and installed defeat devices in certain model year 2014 - 2016 diesel light-duty vehicles equipped with 3.0 liter engines."

Such devices, which can adjust engine performance to produce fewer emissions during offficial tests, violates the US Clean Air Act (CAA), the EPA said.

VW responsed that it "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 embattled German carmaker also said it will cooperate fully with the EPA in the matter.

In September, VW admitted that cars equipped with smaller diesel engines were outfitted with so-called "defeat devices," which helped the vehicles pass US emission tests. The software is also installed on cars in other parts of the world, which VW is addressing through a recall that affects as many as 11 million vehicles worldwide.

The new US allegations not just affect VW brand vehicles, but also involves sister brands Audi and Porsche. The EPA listed specifically:

  • 2014 VW Touareg
  • 2015 Porsche Cayenne
  • 2016 Audi A6 Quattro, A7 Quattro, A8, A8L and Q5.
The EPA said in its statement that the table "represents specific violations that the EPA believes, at this point, are sufficiently supported by evidence to warrant the allegations." It noted that it is authorized to refer the matter to the US Department of Justice "for initiation of appropriate enforcement action."