Element Energy

Element Energy study into real world vehicle emissions and new test cycles published

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Today the UK Committee on Climate Change published a new report by Element Energy and the International Council on Clean Transportation (ICCT) on the real world emissions of light vehicles in the UK. The study builds on previous work that has highlighted a rapidly growing ‘gap’ between official emissions of new cars and vans and their performance in real-world driving.

Previous work on the real world emissions gap used comparisons between official emissions data from vehicle manufacturers and self-reported fuel consumption and emissions data from consumer websites such as Honest John in the UK and Spritmonitor in Germany. Our study employed a complementary approach, examining individual factors that have contributed to the growing gap, from new vehicle technologies to increased exploitation of tolerances in the current test cycle (the NEDC) by manufacturers. Following this analysis of the reasons for the current gap, we assessed the likely future impact of the Worldwide Harmonized Light Vehicles Test Procedure (WLTP), expected to replace the NEDC as the official test procedure for new vehicles from 2017.

Our results suggest that the introduction of the WLTP will reduce the real-world emissions gap from approximately 50% to 23% for new vehicles, by closing loopholes in the current test and better reflecting real world driving. However, the gap is likely to widen again to 30% in the 2020s, as vehicle manufacturers optimise new vehicles to minimise emissions on the WLTP.

Our study also quantified the effect of the real world emissions gap on overall UK emissions for the first time, using a model of the UK light vehicle parc that captures the continual replacement of existing vehicles by new sales. Our modelling shows that a shift to WLTP in 2017 could save 3 million tonnes of CO2 per year by 2020 relative to a continuation of the NEDC. Further improvements in test procedures in the 2020s, for example on road testing of emissions using portable emissions monitoring systems, could increase this saving to 7 million tonnes per year in 2030, equivalent to removing 3 million cars from the road.

The full report is available here and was the basis of a Financial Times article on Monday 7th September 2015.

For further information, please contact the authors Alex Stewart (alex.stewart@element-energy.co.uk) and Alastair Hope-Morley (alastair.hope-morley@element-energy.co.uk).

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