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EU SAM group recommends real driving CO2 monitoring

7 December 2016

The High Level Group of the European Commission’s Scientific Advice Mechanism (SAM) has recently published an opinion on the measurement of CO2 emissions from cars, recommending a monitoring requirement for real driving CO2 emissions (RDE).

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Under the current NEDC laboratory test procedure, there has been a significant and growing gap between the CO2 emissions of light-duty vehicles certified at type approval and their average real-world emissions. The WLTP procedure, based on a more realistic laboratory test cycle, will be introduced in the EU in September 2017. The new procedure is expected to substantially reduce, but not eliminate this gap, noted the SAM report.

The SAM High Level Group report has been prepared to inform the European Commission proposal for post-2020 emission standards for light-duty vehicles, which is expected to be published in 2017. The report concluded that:

The report also identified a number of areas where more scientific and analytical wok is needed. These areas include the development of the ex-post RDE methodology for CO2 emissions, development of a standardized OBD system for fuel consumption monitoring, and development of methods to capture the full life cycle of carbon emissions related to new types of vehicles powered by energy sources other than diesel and petrol.

A recent study by the ICCT has shown that the average gap between passenger vehicle type-approval test results and in-use fuel consumption/CO2 increased to 42% in 2015. According to the ICCT, about three quarters of this gap is explained by vehicle manufacturers exploiting flexibilities in the current type approval procedure (e.g., specially prepared tires or fully charging the vehicle’s battery before testing). The remainder of the gap is explained by the deployment of technologies that have a greater effect on fuel consumption during laboratory testing than under real-world driving conditions (e.g., stop-start technology) and by ensuring that options that tend to increase fuel consumption—such as running the vehicle’s air conditioning—are turned off during laboratory testing.

Source: European Commission