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AIR Index Car NOx Testing

Allow Independent Road-testing (AIR), an independent body comprising concerned citizens who are experts in relevant spheres, have begun real-world road-tests for emission of cars that will be rated on the AIR Index.

The AIR Index rates cars from A (for the best) to E (for the worst). In their own words, AIR say the tests “cut through the politics, the controversy and the commercial conflict to deliver trusted information based on the collective scientific experience and knowledge of the world’s leading experts in air quality and healthcare”. AIR use the latest technology in multiple tests, which enable a prompt and cost-effective approach to clearly define real-world emissions of various cars on sale with a view to immediately address the diesel NOx emissions crisis, in an accessible, transparent and accountable way.

AIR Index Car NOx Testing

AIR is a global initiative that provides a comprehensive and immediate response to reduce air pollution. The development of the AIR Index has been led by the world’s leading academics in the fields of emissions and air quality and they make up AIR’s Scientific Advisory Committee (SAC). The list of members on the committee includes several professors and doctorates from the UK, Germany, Spain, Italy, the Netherlands and the US. They have all reviewed, and support, the rating system, which is based on the latest European CEN methodology CWA17379, and is robust enough for car-makers and policy-makers to take immediate action to solve the NOx crisis.

The A-to-E rating is based on the results of vehicle tests conducted for AIR and carried out on-road, by approved, independent testing organizations. At least two different cars of each model, sold and on the road, are sourced independently from the car makers to ensure that the rating represents the actual emissions produced during town and city driving, with Portable Emissions Measurement System (PEMS) equipment recording on-road driving in towns and cities. For a result to be considered acceptable for rating in the AIR Index there must be at least five 10-km trips completed during three separate journeys on at least two matching vehicles. Each trip takes approximately 20 minutes and is in full compliance with the boundary conditions specified in the protocol. An ‘A’ rating is given to cars that return between 0 and 80 mg/km of measured NOx. Those returning between 80 and 168 mg/km get a ‘B’, 168-270 mg/km get a ‘C’, 270-600 mg/km get a ‘D’, and those above 600 mg/km get an ‘E’.

One of the major manufacturers to reveal their cars’ test figures is Jaguar Land Rover, and they will now display the AIR Index rating for each of the vehicles tested on their UK website.

AIR Index Car NOx Testing

The official NOx limit for diesel-powered cars to comply with the Euro 6 standard is 80 mg/km. Among the tested cars were the Jaguar E-Pace with the ‘D180’ spec 2.0-litre, four-cylinder, turbo-diesel engine which makes 180 PS and 430 Nm. It had figures of just 14 mg/km of NOx and gets an ‘A’ AIR Index rating. Closer to home, the Range Rover Evoque TD4 (with the same powertrain) has received an ‘A’ rating as well. It returned NOx test figures of 17 mg/km. The heavier Discovery with the 3.0 TD6 turbo-diesel V6, meanwhile, returned an appreciably low 33 g/km as well. It is interesting to note that Jaguar Land Rover new diesel engines boast NOx and particulate emissions comparable with petrol cars, but with 15 per cent lower CO2 and 25 per cent better fuel economy.

Massimo Fedeli, Co-founder and Operations Director, Allow Independent Road-testing (AIR), said: “The AIR Index provides easy to understand, at-a-glance information on actual vehicle emissions, from independent testing to help consumers compare vehicles when making buying decisions. Jaguar Land Rover asked us to put a range of their new diesel cars to the test, and the evidence shows that their latest engines are extremely clean, with all of the four models tested achieving the AIR Index A rating, which means that they produce the lowest levels of NOx emissions in urban driving.

“One of the key things to observe from this set of AIR Index ratings is that perceptions of the emissions produced by particular vehicle types, such as SUVs, can be very misleading. In fact, Jaguar’s E-PACE and Land Rover’s Range Rover Evoque are amongst the cleanest cars on sale of any type, not just vehicles within the SUV segment. The perfect example is the Land Rover Discovery, which produced NOx emissions 20 times lower than a diesel Renault Clio supermini.”

The Air Index check is available online at http://www.airindex.com now. Furthermore, if there is a particular vehicle you would like to see tested, the AIR can be informed of it by sending an email to testme@allowair.org for them to consider.

Also read: Diesel, Electricity and Air – a Look at Future Propulsion


About the author: Jim Gorde


Deputy Editor at Car India and Bike India.
Believes that learning never stops, and that diesel plug-in hybrids are the only feasible immediate future until hydrogen FCEVs take over.

t: @CarIndia/@BikeIndia
IG: @carindia_mag/@bikeindia/@jimbosez


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