NOx Emissions from Diesel Passenger Cars Worsen with Age

Yuche Chen, Jens Borken-Kleefeld

Research output: Contribution to journalArticlepeer-review

73 Scopus Citations


Commonly, the NOx emissions rates of diesel vehicles have been assumed to remain stable over the vehicle's lifetime. However, there have been hardly any representative long-term emission measurements. Here we present real-driving emissions of diesel cars and light commercial vehicles sampled on-road over 15 years in Zurich/Switzerland. Results suggest deterioration of NOx unit emissions for Euro 2 and Euro 3 diesel technologies, while Euro 1 and Euro 4 technologies seem to be stable. We can exclude a significant influence of high-emitting vehicles. NOx emissions from all cars and light commercial vehicles in European emission inventories increase by 5-10% accounting for the observed deterioration, depending on the country and its share of diesel cars. We suggest monitoring the stability of emission controls particularly for high-mileage light commercial as well as heavy-duty vehicles.
Original languageAmerican English
Pages (from-to)3327-3332
Number of pages6
JournalEnvironmental Science and Technology
Issue number7
StatePublished - 2016

NREL Publication Number

  • NREL/JA-5400-66153


  • diesel cars
  • light commercial vehicles
  • NOx
  • real-driving emissions


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