VW, Audi Diesels Circumvented Clean-Air Regs

Audi and Volkswagen four-cylinder diesels used software to circumvent federal emissions standards, the U.S. Environmental Protection Agency has alleged.

by Staff

September 18, 2015

VW, Audi Diesels Circumvented Clean-Air Regs — *Photo of 2015 Golf TDI engine courtesy of VW.*

1 min to read

*Photo of 2015 Golf TDI engine courtesy of VW.*

Audi and Volkswagen four-cylinder diesels used software to circumvent federal emissions standards, the U.S. Environmental Protection Agency has alleged.

The cars from the 2009 to 2015 model years included a "defeat device" — a sophisticated software algorithm that detects when the car is undergoing official emissions testing and turns on full emissions controls during that test, according to an EPA violation notice issued Sept. 18. This would violate the Clean Air Act.

The allegations cover about 482,000 models, including the Jetta TDI, Beetle TDI, Golf TDI, and Audi A3 TDI. The Passat TDI is affected from the 2014-MY and 2015-MY.

“Using a defeat device in cars to evade clean air standards is illegal and a threat to public health,” said Cynthia Giles, assistant administrator for the EPA's Office of Enforcement and Compliance Assurance.

In a separate action, the California Clean Air Resources Board has issued an In-Use Compliance letter. CARB has initiated its own investigation in addition to the EPA probe.

"Our goal now is to ensure that the affected cars are brought into compliance, to dig more deeply into the extent and implications of Volkswagen's efforts to cheat on clean air rules, and to take appropriate further action," said Richard Corey, CARB executive officer.

By using the defeat device, the cars will emit nitrogen oxides (NOx) at up to 40 times the regulatory standard during normal operating conditions, according to the EPA.

Volkswagen must now offer a fix for affected models, which remain legal to drive and resell. Volkswagen had not commented publicly on Sept. 18.

EPA and CARB uncovered the defeat device software after independent analysis by researchers at West Virginia University, working with the International Council on Clean Transportation, a non-governmental organization, raised questions about emissions levels. The agencies began further investigations into the issue. In September, after EPA and CARB demanded an explanation for the identified emission problems, Volkswagen admitted that the cars contained defeat devices, according to EPA.

Read the EPA's full release here.

Topics:Clean Air Act CARB Volkswagen Emissions 2009-MY Audi VW Diesel Scandal EPA 2015-MY Green Fleet

More Green Fleet

Rendering of electric vehicles charging beneath a solar-panel canopy, illustrating Inspiration Mobility Group’s acquisition of Electrada assets to expand commercial fleet electrification services.

Green Fleet•by News/Media Release•June 17, 2026

Inspiration Mobility Acquires Key Electrada Assets

Inspiration Mobility Group has acquired select assets of Electrada, adding the fleet electrification provider's team, technology, and charging infrastructure development capabilities to its energy management business.

Turning Connected Vehicle Data Into Decisions That Matter

Fleet leaders have more data than ever, but turning that data into clear, actionable decisions remains a challenge. This white paper shows how leading organizations are using connected vehicle data to improve safety, reduce costs, and optimize fleet performance. Learn how to turn insight into action across your fleet.

Are You Tracking Your Fleet's True Total Cost of Ownership?

Bobit Business Media surveyed 190 fleet professionals and found that while most fleets are tracking costs, fragmented systems and data gaps are keeping true TCO visibility out of reach. With rising pressure to control spend in an increasingly volatile environment, the gap between what fleets think they know and what the data actually shows is wider than you might expect. See how your peers are managing costs today and where the industry still has room to improve.

Hybrids: Electrification Without the Challenges

For fleet managers, fuel is one of the biggest line items in the budget — and it's one hybrids can shrink without changing how your people work. Download the eBook to see the numbers, understand the technology, and get a step-by-step guide to making the switch.