Volkswagen Dieselgate: emissions defeat devices

The allegation

Software in certain VW diesels recognized tests and altered controls to pass laboratory limits while producing more NOx on roads. This does not implicate every diesel.

Timeline

Independent road tests raised concerns in 2014. EPA notice came in 2015; VW pleaded guilty to U.S. criminal charges in 2017, followed by recalls and settlements.

What the record establishes

EPA notice, VW plea, and court records document the device and covered cars. ICCT road testing supplied independent technical evidence.

Counterevidence and alternative explanations

Coverage varied by model, year, and market. Road emissions vary with route, temperature, and maintenance.

Uncertainty and limits

Tests cannot represent every trip; admissions concern defined conduct and jurisdictions.

Calibrated skeptical verdict

Test circumvention in charged vehicles is established. A universal industry conspiracy requires manufacturer-specific proof.

What could change the assessment

Source code, internal approvals, and independent fleet testing could clarify scope and revise emissions estimates.

Annotated authoritative sources and source limits

1. EPA violation noticePrimary regulator account of affected vehicles.
2. DOJ VW plea (2017)Criminal admissions and defined offense scope.
3. ICCT road testsIndependent testing of sampled vehicles and conditions.