What looks wrong
A family car advertised as the rare diesel that was good for the planet and fun to drive.
What’s actually going on
On 18 September 2015 the EPA issued a Clean Air Act notice of violation: Volkswagen had installed defeat-device software in model-year 2009–2015 2.0-liter diesels that met the lab test and then emitted up to 40 times the legal NOx on the road. VW later admitted the software. The cars stayed driveable; the claim did not.
For years Volkswagen sold TDI cars in the United States as 'clean diesel' — the grown-up answer if you wanted torque without the gasoline guilt. The ads did the moral work. The software did a different job.
EPA's 18 September 2015 notice said model-year 2009–2015 four-cylinder VW and Audi diesels contained software that could tell a lab test from a road. In the lab, emissions controls behaved. In the world, the agency said, NOx could run up to 40 times the certified limit. Defeat devices are not allowed on certified cars. Independent work by West Virginia University researchers, with the International Council on Clean Transportation, is what first made the agencies look.
Volkswagen later admitted the software to EPA and California. Settlements included buybacks, modifications, mitigation money, and criminal resolutions documented on EPA's Volkswagen pages. This story is the press-release-versus-the-code problem: a public green claim, a hidden switch. No owner is the punchline.
Source: EPA, Learn About Volkswagen Violations. We quote the public record. A settlement is not always an admission.