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Air Index launches on-road, independent guide to tailpipe emissions

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A new standardised emissions rating system which allows fleet managers to see how much pollution a vehicle produces when used in urban areas has been launched.

Air Index is an independent alliance of public and private organisations, which promotes the voluntary uptake of independent on-road emissions testing.

It tests at least two cars, sourced independently from vehicle manufacturers, with portable emissions testing units (PEMS) recording actual on-road driving in towns and cities.

The results are then shown through an A to E colour-coded rating to show the difference between clean and dirty vehicles and has been created to inform buyers and city policy.

Nick Molden, co-founder of AIR said: “The transparent publication of independent, on-road emissions testing results is the most efficient way to improve air quality.

“The AIR Index removes the confusion among car buyers and policy makers around petrol and diesel emissions, and around testing processes.

“Our tests go further than current car approval testing WLTP (Worldwide Harmonised Light Vehicle Testing Procedure) and RDE (Real Driving Emissions).

“WLTP is a step in the right direction but is still conducted in the laboratory and is not fully independent.

“RDE comes too late to solve the problem of very high NOx emitting diesel vehicles driving through our towns and cities.

“In our testing, we have found a number of the newest Euro 6 cars still emit significantly more NOx on the road than in the laboratory test used for their type approval.

“Our tests also reveal some diesel cars cleaner than petrol ones and some older cars are cleaner than newer ones.

“Change is already underway for new diesel cars and we believe the AIR Index can accelerate that change with car makers and policy makers aligned to changing our cities’ air quality – for the better.”

So far, six vehicles have been tested by AIR, and rated in the AIR Index are:





AIR Index


Fuel Type

Official  NOx limit

Euro Standard

Land Rover

Discovery 3.0 TD6




80 mg/km

Euro 6


Qashqai 1.2 DiG-T




60 mg/km

Euro 6


Cooper S 3dr 2.0 d  




80 mg/km

Euro 6


Duster 1.5 DCI




80 mg/km

Euro 6


Focus 1.5 TDCI




80 mg/km

Euro 6


Clio 1.5 DCI




80 mg/km

Euro 6



AIR has now commissioned a programme of vehicle testing and more results will be added to the AIR Index periodically.

Gerry Keaney, chief executive of the BVRLA, added: “Companies engaged in vehicle rental, leasing and fleet management will welcome the transparency on urban NOx emissions provided through the AIR Index.

“This is a win-win solution for fleet owners and policy makers, offering independent guidance to select the cleanest vehicles which will improve air quality now.

“The Index should not be used to create retrospective air quality policies that would punish fleets for vehicle choices they have already made based on less accurate NOx data.”




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