Skip to main content

Are all diesels dirty? EPA calls out fancy Porsche Audi VW diesels

EPA issues its second Notice of Violation to the Volkswagen group. This time it is the pricey six-cylinder diesels EPA says are dirty.


Yesterday the Environmental Protection Agency (EPA) in cooperation with the California Air Resources Board (CARB) accused Porsche, Audi, and parent Volkswagen of installing a cheating device on the companies' three-liter diesels. The EPA Notice of Violation (NOV) accuses VW of producing engines that are nine times dirtier than gasoline engines.

How the Dirty Diesels Cheat
The recent NOV spells out how the vehicles behave in plain English saying:
“When the vehicle senses that it is undergoing a federal emissions test procedure, it operates in a low NOx “temperature conditioning” mode. Under that mode, the vehicle meets emission standards. At exactly one second after the completion of the initial phases of the standard test procedure, the vehicle immediately changes a number of operating parameters that increase NOx emissions and indicates in the software that it is transitioning to “normal mode,” where emissions of NOx increase up to nine times the EPA standard, depending on the vehicle and type of driving conditions. In other tests where the vehicle does not experience driving conditions similar to the start of the federal test procedure, the emissions are higher from the start, consistent with “normal mode.”

Back in late September EPA told all automakers that it would be looking closely at the diesel vehicles in their fleets to ensure that they complied with the law. VW has admitted to installing a device that cheated on emissions, but until yesterday that was limited to the most common diesel engine the company sold, a two-liter diesel in mid-size and smaller cars. Now EPA says that the larger diesel used in its bigger vehicles like the Porsche Cayenne are also cheating and polluting at about one order of magnitude greater than allowable by law.

Cynthia Giles, Assistant Administrator for the Office for EPA’s Enforcement and Compliance Assurance, said in a press statement, “VW has once again failed its obligation to comply with the law that protects clean air for all Americans. All companies should be playing by the same rules. EPA, with our state, and federal partners, will continue to investigate these serious matters, to secure the benefits of the Clean Air Act, ensure a level playing field for responsible businesses, and to ensure consumers get the environmental performance they expect.”

New Dirty Diesel VehicleList
Vehicles included in the EPA’s latest NOV are the pricey models below. Unlike the mainstream models, VW’s brands sell barely any of these, but the allegations implicate some of the company’s fanciest models.
-- 2014 VW Touareg
-- 2015 Porsche Cayenne
-- 2016 Audi A6 Quattro, A7 Quattro, A8, A8L, and Q5

This latest accusation casts more doubt on the drivability and fuel economy of all diesels when they comply with the same rules that gasoline engines do. In the U.S. market, the vast majority of diesel-equipped passenger cars and SUVs are made by the VW group. Mercedes, General Motors and BMW's diesel fleet is tiny by comparison. Porsche released a statement this morning saying, “We are surprised to learn this information. Until this notice, all of our information was that the Porsche Cayenne Diesel is fully compliant.”

Read the full EPA statement.