All Euro 6 diesels exceed NOx limits in real-world driving

The latest Euro 6 diesel engines are exceeding official NOx emissions limits, despite claims to the contrary by manufacturers. That's according to a new study by the TRUE initiative - an independent automotive emissions body.

Models were tested in real-world driving conditions, and have been rated in a colour-coded system - red (poor), yellow (moderate), and green (good). All Euro 6 petrol models received a good or moderate rating, with the majority classed as good. However, almost all the diesel vehicles tested were rated as poor, with a handful classed as moderate.

The vehicle ratings are available online in a searchable database on the TRUE initiative website. TRUE is a partnership between the FIA Foundation, the International Council on Clean Transport (ICCT), the Global New Car Assessment Programme, Transport and Environment, and C40 Cities. The aim of the initiative is to bring transparency to vehicle emissions and urban air quality.

Ratings have been calculated for around 4,850 vehicles, with almost all of them fitted with engines built to Euro 3-6 standards. All diesels exceeded the Euro 6 NOx emissions limits in real-world conditions, with the highest-emitting Euro 6 petrol having around the same level of NOx emissions as the lowest-emitting diesels.

TRUE Initiative ratings

The above image represents passenger cars rated in the TRUE system, grouped by fuel type and Euro standard. The red category includes both cars that only slightly exceed the rating's threshold for NOx emissions (180 g/km, equivalent to the Euro 5 type- approval limit for diesel cars, which all new cars should theoretically have met for at least seven years) and gross emitters that exceed the regulatory limit by 18 times or more. Nearly all diesel vehicles on European roads today received a "poor" rating, meaning they exceed the Euro 5 diesel NOx emissions limits introduced in September 2009.

Four manufacturer groups had average emissions more than 12 times above the Euro 6 diesel limits, and the highest-emitting vehicle family was at 18 times the limit.

Euro 5 diesel engines performed the worst out of the standards, with all producing NOx emissions at least twice the limit, and the worst 18 times what the regulations allow.

Rachel Muncrief, program director for the ICCT, said: "This initial project is an important first step, but remote sensing could take us very much further in terms of our ability to monitor, analyze, and control vehicle pollutant emissions and gain control of Europe's urban air-quality problem."

The initial data set comprises samples collected in France, Spain, Sweden, Switzerland, and the United Kingdom over ten years and pooled together in the CONOX project, funded by the Swiss Federal Office for the Environment.

The data set presently holds ~750,000 records. The TRUE ratings were developed from a subset of ~375,000 measurements, excluding trucks and vans and any incomplete measurements. It is the largest collection of data brought to bear thus far on the problem of air pollution from vehicles in Europe.

Find out more about TRUE ratings here.

Top image: a Peugeot 508 fitted with PEMS equipment for real-world emissions testing - the PSA Group has committed to releasing real-world emissions and fuel economy figures for all its models.

Find out more about emissions here

Chris Lilly

Author:Chris Lilly
Date Updated:6th Jun 2018

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