28 Feb 19

AIR Index unveils real emissions

Henceforth, there will be clarity about the real emissions of cars. The newly published AIR Index allows fleet managers and others to consult an independent, standardised on-road car emission rating system. 

Clearing the Smog

The independent AIR Index can be consulted from today. The Index shows the actual nitrogen oxides (NOx) emissions for each vehicle type tested. The A-E colour-coded rating is a non-nonsense rating system endorsed by global air quality and vehicle emissions experts. As such the AIR Index allows consumers and policy makers to verify the tailpipe emissions of a car before buying and even to simply compare with other vehicles.

The system is inspired on the American NCAP system, an independent vehicle-safety rating index. Which aimed to hold car makers responsible for the safety of their models through unveiling the real safety issues of the vehicles. As a result, many carmakers adopted voluntary additional safety measures. The AIR Index might have the same effect. Additionally, it gives policy makers and car buyers and fleet managers the opportunity to make real sustainable choices in terms of air quality. 


The independence of the system is highly valuable since the lately Dieselgate and other scandals in which OEMs failed to communicate the correct emissions of their models. Moreover, with the increasing environmental restrictions and emission regulations such as WLTP in Europe, having clarity on the real emissions of your car is a must. 

The data in the AIR Index is not obtained via the OEMs solely but based on on-road vehicle testing according to the latest CWA 17379 methodology. The tests were conducted on the road in real driving conditions and compared by tough but fair testing criteria, which applied to each different car type. 


The real-road conditions are crucial since tests in laboratories tend to underestimate the real emissions. For Nick Molden, Co-founder of AIR, the AIR Index takes the current emission standard measures a step further. ‘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.’    

Remarkable findings

For the latter, the AIR Index has discovered that even a number of the newest Euro 6 cars still emit more NOx on the road than in the laboratory test, even though those tests were used to obtain their type approval.
Further on, the AIR Index unveiled that some diesels are cleaner than petrols, and some older cars are cleaner than newer ones. Hence, an independent rating mechanism of the current vehicle emissions is a necessary and useful tool that will serve policy makers, fleet managers and car buyers in general to make the right decision – based on the right information.

Image: The AIR Index uses a code-colour index to easily consult the real emissions of a car.

Authored by: Fien Van den steen