The EQUA Air Quality Index rating scheme has been launched to help clear the confusion over real-world NOx emissions.

Recent headlines have highlighted the issue that real-world emissions can be four times or more higher than official NOx emissions figures and the EQUA Air Quality Index aims to help monitor vehicle performance when driven normally on roads, and the effectiveness of the forthcoming Real Driving Emissions regulations for new vehicle certification.

The ratings, which have been developed by Emissions Analytics, are freely available to all, with a sticker showing each car’s performance.

The first set of more than 440 ratings is available now and the programme will continuously add new vehicles to its database.

An advisory board of leading academic and industry experts has been assembled to review the test and rating methodology and provide input into the wider development of the programme. The board includes individuals from Imperial College London, King’s College London, the International Council on Clean Transportation and the University of Cambridge.

Nick Molden, CEO and founder of Emissions Analytics, said: “There’s a great deal of confusion among car buyers on the subject of pollutant emissions, but we’re able to deliver impartial and precise information to help them buy better. We’re also looking forward to working with the industry as a whole to highlight the best vehicles available.”

On the launch of the programme, Steve Gooding, director of the RAC Foundation, said: “This work is a welcome attempt to decipher a very complex set of air quality regulations and test results, and present them to motorists wanting to buy a clean car. It should also be required reading for manufacturers as it demonstrates that diesel cars can score well in real-world driving conditions. However, the star performers in the diesel category are few in number and these figures send out a strong message to several auto makers that they need to up their game.”