On-road testing of CO2 and exhaust emissions from Euro 6 passenger cars in the EU

Published: 2016.11.14

Emissions Analytics

In 2015, the ICCT commissioned Emissions Analytics, a commercial test house specializing in testing real-world fuel consumption and emissions, to perform on-road testing of Euro 6-regulated gasoline and diesel vehicles. Emissions Analytics tested 7 vehicles between 2015 and 2016 for emissions of carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), nitrogen dioxide (NO2), and particulates. The vehicles selected for testing were a Ford Focus, Volkswagen Golf, Citroën C4, Mercedes-Benz C220, Vauxhall/Opel Astra, Volkswagen Transporter and Volkswagen Caddy C20. The Ford Focus and the Volkswagen Golf were gasoline direct injection vehicles, while the rest were diesel. The detailed testing results can be found in the full report available for download above.

Overall, emissions of NOx and CO2 varied greatly, although all Volkswagen diesel vehicles and both gasoline vehicles fell below, or very close to, the future RDE conformity factors for NOx. These findings indicate that low real-world NOx emission levels are achievable with current technology, if applied correctly. The implementation of the RDE test procedure, beginning in 2017, is expected to improve NOx emission performance in vehicles, even though the current definition of conformity factors and boundary conditions is expected to limit the short term impact of the RDE regulation for reducing on-road NOx emissions of the vehicle fleet. As for CO2, the European Commission will implement a new Worldwide Harmonized Light Vehicles Test Procedure (WLTP) in 2017 that is expected to help reduce the discrepancy between official and real-world CO2 emission levels. However, to prevent the CO2 discrepancy level from increasing again in future years, in-use conformity testing for CO2, similar to the RDE test procedure for air pollutants, will be a cornerstone for further reducing on-road CO2 emission levels of new vehicles. Finally, the PN results in this study suggest that for at least some gasoline direct injection vehicles, further reduction fine and ultrafine particulates will be necessary under upcoming regulations, either through the use of a more advanced injection technology that produces fewer particulates or a gasoline particulate filter.