DIESELGATE AND VOLKSWAGEN: THE GLOBAL DECEPTION OF CLEAN DIESEL.

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I. An exemplary ruling.

On May 26, 2025, the Regional Court of Braunschweig (Lower Saxony, Germany) convicted four former executives of the Wolfsburg automotive group for fraud.

A former head of diesel engine development was sentenced to four and a half years in prison. Two years and seven months of imprisonment were imposed on the former head of propulsion electronics. The highest-ranking defendant, a former member of Volkswagen’s Board of Management, received a one year and three months suspended sentence. A former department head was sentenced to one year and ten months suspended.

The verdict comes nearly ten years after U.S. authorities uncovered manipulated software—known as a defeat device—installed on the group’s Turbocharged Direct Injection (TDI) diesel vehicles, designed to cheat nitrogen oxide (NOx) emissions tests.

Another piece, then, in the complex mosaic of the Dieselgate scandal, which cost the famous automotive group not only its reputation but also several billion dollars.

But when did it all start?

II. The great clean diesel fraud and the defeat devices.

In 2013, the International Council on Clean Transportation (ICCT), a U.S. non-profit organization, commissioned the Center for Alternative Fuels, Engines and Emissions at West Virginia University (WVU) to conduct on-road emissions tests of diesel engine cars sold in the United States.

The premise of this research was simple: the organization aimed to demonstrate that the latest generation diesel engines complied with the stringent U.S. emission standards, promoting the idea of “cleaner diesel.”

However, the tests revealed that two out of three vehicles produced by the well-known Wolfsburg manufacturer (initially anomalies were detected only on the Jetta and Passat models) emitted additional nitrogen oxide (NOx) compared to the officially declared values.

Specifically, on-road emissions were found to be 40 times higher than the legal limits then in force in the USA.

With this premise, in May 2014 the ICCT published the test results and alerted the California Air Resources Board (CARB) and the U.S. Environmental Protection Agency (EPA), which subsequently announced formal investigations against Volkswagen.

In September 2015, the EPA officially confirmed Volkswagen’s violation of the Clean Air Act.

After some hesitation, the German automaker formally admitted to having installed illegal software (defeat devices) in a large part of its diesel and TDI diesel vehicles. In addition to the Jetta and Passat models, the tampering affected the best-selling Golf, Tiguan, Polo, and New Beetle models.

But what exactly is a defeat device?

A defeat device is software installed in a vehicle’s control unit designed to improve the performance of the emission control system during certification tests.

This software relies on an algorithm that detects driving conditions, allowing the vehicle to recognize when it is undergoing an official test (such as laboratory tests) and to activate a “clean” driving mode only at that time, reducing emissions to comply with legal limits.

Otherwise, if the software detects that the vehicle is on the road, it disables or reduces anti-pollution technologies to improve engine performance, reduce fuel consumption, or extend the life of certain components.

It is essential to specify that the defeat device distinguishes different driving conditions (on-road or during laboratory testing) by analyzing several parameters such as:

Steering wheel position: during tests, the steering wheel is perfectly straight.
Vehicle speed: tests follow standardized cycles, the most common being the Urban Dynamometer Driving Schedule (UDDS), a dynamometer bench simulation that reproduces typical urban driving behavior.
Test duration: cycles are precise and repeatable (e.g., about 20 minutes).
Acceleration/braking: very regular and predictable.
Air temperature and pressure: typical of closed, controlled environments (like laboratories).

When these parameters are simultaneously detected, the software understands the vehicle is undergoing a laboratory test and activates the anti-pollution technologies.

What are the specific reasons behind the installation of defeat devices?

Leaving aside easy accusations, it is important to understand the reasons the German automaker put forward to justify the manipulation software on some of its flagship vehicles.

They argued that the purpose was to preserve the engine, reduce aging, and ensure safer and proper operation.

Specifically, Volkswagen stated that emission control systems (such as EGR, Exhaust Gas Recirculation, or SCR, Selective Catalytic Reduction for urea/AdBlue) could damage the engine or reduce its lifespan if used continuously or under unfavorable environmental conditions.

For example, at low temperatures, recirculated exhaust gas can condense and form acidic residues (such as nitric acid), which corrode valves or ducts. Excessive use of EGR can increase soot buildup (particulate matter) and clog the diesel particulate filter (DPF).

Furthermore, the systematic use of emission manipulation systems would have been allegedly endorsed by European emission legislation, specifically Article 5, paragraph 2, letter a) of Regulation (EC) No. 715/2007 of June 20, 2007, which states:

“… The use of defeat devices that reduce the effectiveness of emission control systems is prohibited. This prohibition does not apply when: a) the device is justified by the need to protect the engine from damage or failure and ensure the safe operation of the vehicle …”

No fraudulent intent, therefore, but merely a desire to protect consumer safety and increase engine durability.

III. A necessary turning point: The CJEU ruling, Case C-693/18 of October 17, 2020.

Although the aforementioned Braunschweig Regional Court ruling is an important legal precedent, it is not the only noteworthy decision in the saga that marked the decline of the Wolfsburg automaker.

For illustrative purposes and to clarify what has been stated, the author wants to highlight the CJEU ruling of October 17, 2020, in case C-693/18 concerning the marketing and sale in France of Volkswagen vehicles equipped with defeat device software.

At the request of the investigating judges of the Tribunal de grande instance de Paris (Paris Court of First Instance), the Court crystallized the concept of a defeat device in relation to the violation of Regulation (EC) No. 715/2007 of June 20, 2007 (on type approval of motor vehicles concerning emissions from passenger cars and light commercial vehicles Euro 5 and Euro 6 and the availability of vehicle repair and maintenance information).

Specifically, the European Judge clarified that:

“… 102 … In the light of the foregoing, the answer to parts (a) and (c) of the third question is that Article 3(10) of Regulation No 715/2007 must be interpreted as meaning that a device which detects any parameter related to the conduct of the approval procedures provided for by that regulation in order to improve the performance of the emission control system during those procedures, and thus obtain approval of the vehicle, constitutes a ‘defeat device’, within the meaning of that provision, even if such an improvement may also be observed, occasionally, under normal conditions of vehicle use …”

Furthermore, the Court examined whether the manipulation devices—installed knowingly on vehicles—constitute a specific violation of Regulation (EC) No. 715/2007. Regarding this, the Court ruled:

“… 112. Since Article 5(2)(a) of Regulation No 715/2007 constitutes an exception to the prohibition on the use of defeat devices which reduce the effectiveness of emission control systems, it must be interpreted strictly. … 115. In the light of the foregoing considerations, the answer to Question 3(a) and Question 4 is that Article 5(2)(a) of Regulation No 715/2007 must be interpreted as meaning that a defeat device, such as that at issue in the main proceedings, which systematically improves the performance of the emission control system of vehicles during type-approval procedures in order to comply with the emission limits laid down by that regulation, and thus obtain the approval of those vehicles, cannot fall within the scope of the exception to the prohibition on such devices laid down in that provision, which relates to the protection of the engine against damage or accident and the safe operation of the vehicle, even if that device helps to prevent the ageing or clogging up of the engine. …”

In other words, the Court of Justice of the European Union rules that the systematic and programmed use of defeat does not reflect a real need to protect the engine, but rather a way to pass emissions controls. According to the Court, this systematic use is not even supported by the relevant European legislation (i.e., Regulation (EC) 715/2007).

IV. The disastrous economic fallout and the strategic changes of the automotive group.

Data show that the Dieselgate scandal cost Volkswagen much more than its reputation.

In the United States alone, the Wolfsburg company has paid about 25 billion dollars in fines, compensation, legal expenses, and vehicle buybacks/repairs.

In Europe, where class action laws are less favorable, Volkswagen has still paid millions of euros in compensation following collective lawsuits (e.g., in Germany and Italy).

In Italy, Altroconsumo, a consumer protection association, and Volkswagen reached an agreement of about 50 million euros for refunds to owners of the German automaker’s vehicles; each individual owner who accepts the offer may be reimbursed with an amount ranging from 550 to 1,100 euros.

Paradoxically, what turned out to be one of the most serious industrial scandals of the 21st century also triggered one of the most radical transformations in Volkswagen’s history. Forced to pay the price for a compromised reputation and the resulting loss of consumer trust, the German car manufacturer reacted with a decisive strategic shift: massive investment in electric mobility.

Starting in 2016, Volkswagen announced ambitious plans to convert its production lines, develop a modular platform dedicated to electric vehicles (the MEB), and launch a new generation of zero-emission cars.

With investments exceeding 60 billion euros in research, innovation, and sustainability, the group has made ecological transition its redemption goal, aiming to become the global leader in electric mobility within the next decade.

In this sense, Dieselgate forced the German automaker into a necessary ethical and environmental reflection, pushing it to rethink mobility solutions that are not only more efficient but also more ecological.