Press release 2018-08-17

European study shows diesel car emission levels

An IVL-led study has compiled emissions data from over 700,000 vehicles in Spain, Sweden, Switzerland and the UK. The results show that NOx emissions from diesel vehicles haven’t significantly changed between the Euro 1 and 5 emission standards, despite rigorous EU emission regulations. It is only with the advent of the latest Euro 6 standard that there has been some improvement, though new diesel cars still release about five times as much NOx as required by law.

– Legislation and previous emission controls have unfortunately not worked as well as intended. At long last Euro 6 cars are beginning to deliver, but it there is still a long way to go before the expectations imposed by the legal requirements are met, says Åke Sjödin, emissions expert at IVL Swedish Environmental Research Institute.

In the study, emission data from over 700,000 vehicles has been compiled and analyzed for atmospheric pollutants such as nitrogen oxides and particles. The measurements have been carried out between 2011 and 2017 under real-time traffic conditions in Spain, Sweden, Switzerland and the UK, and the report covers emission data for all euro classes and targets a wide range of different car brands and models.

– This large database allows us to make more accurate analyses. It also lets us compare emissions performance between different countries and understand the importance of a common European emission standard, says Åke Sjödin.

A particular focus of the study has been to evaluate the actual emissions of diesel cars, especially those classified according to the Euro 5 and 6 emission requirements. Analysis of more than 200,000 diesel vehicles shows that emissions of hazardous NOx gasses under real driving conditions have not been affected by EU emissions rules and have remained largely unchanged between the Euro 1 and Euro 5 classes.

This means that the average European diesel-powered Euro 5 car emits in real-life between five and six times as much NOx gasses as the Euro 5 standard requires. Some car models exceed the stipulated limit by as much as forty-fold. The level of emissions is also affected by ambient temperature, rising sharply when the temperature drops below 20 degrees Celsius and increasing even when the temperature is above 25 degrees.

Diesel cars in the latest environmental class, Euro 6, do much better. On average, they release about half as much NOx gasses as Euro 5 cars. But despite improvements, emissions are still far too high – in real traffic NOx limits are exceeded roughly five-fold, the study thus confirms previous measurements carried out in Sweden by IVL.

When it comes to particulate matter, the study shows that the introduction of efficient diesel particulate filters in conjunction with new emission standards has effectively reduced real emissions to extremely low levels for Euro 5 and 6 cars.

The study has been funded by the Bundesamt für Umweltschutz (BAFU – the Swiss equivalent of the Swedish Environmental Protection Agency – and carried out in cooperation with, among others, IIASA, ICCT, the Universities of Leeds, York and Graz and Opus International Consultants.

Download the report here.

For more information, please contact:
Åke Sjödin, ake.sjodin@ivl.se, +46 (0)10-788 67 98