Institute for Transport Studies (ITS)

Implications of the VW scandal: studies on exhaust emissions

Dr James Tate 

The Institute for Transport Studies has been surveying the Real Driving Emission (RDE) performance of the UK vehicle fleet for several years. By scanning through the exhaust plume trailing a vehicle as they drive through a measurement station, and knowing each vehicle’s specification (e.g. 2012, 2.0 litre diesel car, Audi A4) from its number plate, the Real Driving Emission performance of groups, types or those equipped with the Volkswagen EA189 Euro V diesel engine for example can be assessed.

Audi, Seat, Skoda and Volkswagen cars equipped with the offending EA189 2.0-litre Euro 5 diesel engine with 'defeat device' were extracted from the Real Driving Emission measurements made across the UK in 2015. The 643 cars surveyed with the EA189 engine were compared with measurements from 2.0-litre Euro 5 diesel from other manufacturers (ALFA ROMEO, BMW, CHEVROLET, CITROEN, FIAT, FORD, HYUNDAI, KIA, MERCEDES-BENZ, MINI, NISSAN, PEUGEOT, RENAULT, SAAB, SSANGYONG, SUBARU, TOYOTA, VAUXHALL, VOLVO – total 785).

In real, urban driving conditions the EA189 2.0-litre Euro 5 diesel engine was emitting approximately 35% LESS NOX per kilometre of driving than from 2.0-litre Euro 5 diesel cars from other manufacturers. If other manufacturers are not fitting ‘defeat devices’, they are still manufacturing and setting up cars to emit high amounts of the air quality pollutant NOX in real urban driving conditions.

The latest generation of Euro VI diesel cars do emit ~50% less NOX per kilometre of driving than their predecessors (Euro I, II, III, IV, V) but still on average 5 times that permitted by the Euro VI standard (0.08g.km-1 in the laboratory, over the NEDC drive cycle). NOX emissions from Euro VI petrol cars (ALL manufacturers) were measured to be low and at a level close to their Euro VI emission standards (0.06g.km-1).

Euro V (2009-2014) 2.0-litre diesel cars

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The Institute for Transport Studies has been surveying the Real Driving Emission (RDE) performance of the UK vehicle fleet for several years. By scanning through the exhaust plume trailing a vehicle as they drive through a measurement station, and knowing each vehicle’s specification (e.g. 2008, 2.0 litre diesel car, Audi A4) from its number plate, the research has demonstrated that NOX emissions from all types of diesel vehicles in urban driving conditions have changed little in the past 15-20 years. The remote sensing surveillance approach can measure the emission performance of thousands of vehicles a day, in stark contrast to the small numbers of vehicles tested in laboratories, or on-the-road with Portable Emission Measurement System (PEMS) equipment.

Over 700 new cars registered as complying with the latest September 2014 Euro VI emission standards have been measured this year. The NOX emissions from Volkswagen diesel passenger cars per kilometre driven in real, urban driving conditions were observed to be 5 times the amount permitted by the Euro VI standard (0.08g.km-1 in the laboratory, over the NEDC drive cycle). These results are in-line with recently published results from www.theicct.org and www.transportenvironment.org. Volkswagen is not alone in disregarding passenger car Real Driving Emissions (RDE) and the quality of air in our towns and cities. There was little discernible difference in the NOX performance of Euro VI diesel cars between the major manufacturers surveyed. NOX emissions from all petrol cars were measured to be low and at a level close to the Euro VI emission standards (0.06g.km-1).

The European Commission has been debating the discrepancy between Real Driving Emissions (RDE) and regulatory, laboratory testing since at least 2007. It is imperative that the planned 2017 implementation date for RDE regulations is not delayed any longer. In the interim Cities are left with the latest small city diesel cars emitting more NOX per kilometre driven than Euro VI compliant Double-decker Buses or fully laden 40 tonne articulated Lorries.

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