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Reassessment of excess NOx from diesel cars in Europe following the Court Justice of the European Union rulings

Vehicle testing

The Court of Justice of the European Union (CJEU) clarified the definition of a prohibited defeat device in a series of recent rulings, limiting their use to when “only immediate risks of damage” are present. This report analyzes testing data and examines market surveillance interviews to determine how many vehicle models likely have defeat devices under the CJEU definition. Results are analyzed by vehicle model and engine family against emission thresholds developed in this report which identify if a prohibited defeat device is likely or almost certainly present. These thresholds are based on expected engine behavior and testing data from other vehicle groups.

“Suspicious” NOx emission levels were found in 77%–100% of tests and vehicle averages, indicating the likely use of a prohibited defeat device. Of 1,400 total tests conducted under controlled settings by government authorities, 85% of tests on Euro 5 vehicles and 77% of tests on pre-RDE Euro 6 vehicles exceed the suspicious emissions threshold. Similar rates are observed for government tests conducted under real-world conditions. Results from independent real-world testing show that up to 100% of vehicle model averages exceed the suspicious threshold.

“Extreme” NOx emissions were found in 40%–75% of tests and vehicle averages, indicating that a prohibited defeat device is almost certainly present. Approximately 42% of the 1,400 official government tests under controlled settings exceed the extreme threshold. Real-world testing by government authorities and independent bodies shows similar or higher rates of extreme emissions. Remote sensing data show that approximately 75% of engine family averages exceed the extreme threshold.

Over 200 unique vehicle models show high NOx emissions above the “suspicious” threshold and over 150 unique vehicle models show NOx emissions above the “extreme” threshold. Nearly all vehicle models tested by official government authorities show suspicious emissions in at least one test, and nearly 70% of vehicle models showed extreme emissions in at least one test.

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