Washington - Volkswagen used devices to cheat air pollution tests in diesel luxury vehicles in model years 2014 through 2016, US and California environmental regulators said on Monday, widening their investigation into the carmaker's emissions scandal.
The US Environmental Protection Agency said it is now looking at 3.0-litre V6 diesel engines used mostly in larger, more expensive models like the Porsche Cayenne sport utility vehicle in addition to the smaller diesel engines whose test-deceiving software were initially targeted by the agency.
The move pulls luxury brands Porsche and Audi deeper into the scandal that has already engulfed the corporate parent Volkswagen AG and its mass-market VW brand. On the road, emissions of the smog-causing pollutant nitrogen oxide on the affected high-end vehicles could be nine times higher than allowed, the EPA said.
"The latest revelations raise the question, where does VW's road of deceit end?," House Energy and Commerce Committee Chairperson Fred Upton said in a statement, adding that the disclosure "prompts questions regarding the prevalence of the emissions cheating and how it went undetected for so long."
Volkswagen said in response to the EPA allegations that it had installed no software on its 3.0 litre V6 diesel cars to improperly change emissions values and that it was cooperating with the agency to fully investigate the matter.
About 10 000 of the luxury cars are fitted with the illegal software device, regulators said. Many more may be on the road. VW in 2013 said it had built and sold more than 1.6 million 3.0 V6 TDI engines worldwide, just before the current version of the engine was introduced in 2014.
It is not clear how many models fitted with the current version may have the illegal software. The EPA said it cited only those vehicles and model years that it had recently tested. It did not say if it has tested earlier versions of the 3.0 TDI.
In September, Volkswagen admitted it installed software that can cheat emissions tests, called defeat devices, in smaller, four-cylinder engines on about 482 000 cars in the United States and more than 11 million worldwide.
Among the diesel models officials named on Monday as being in violation of US laws are five Audi models, including the A6 sedan and the Q5 SUV. Also cited were the VW Touareg and Porsche Cayenne.
The emissions cheats allowed the vehicles to pass tests meant to monitor vehicles' emissions of nitrogen oxide.
The mechanism detects when an engine is being tested for tailpipe emissions and then alters the emission controls to permit more pollutants in actual driving.
Car makers are permitted to use software to optimize engine performance in some cases, but sidestepping emissions controls with a defeat device is prohibited by law.
Volkswagen has yet to come up with solutions to address illegal software on three generations of four-cylinder diesels first cited by the EPA on September 18.