Many new diesel cars are still exceeding emission limits despite having passed official tests, according to independent tests.
The EQUA Air Quality Index has been developed by Emissions Analytics, and aims to measure emissions in real-life on-the-road driving rather than the laboratory-based test used for the Euro-6 standards.
The company tested more than 20 new cars during August and reported that Volkswagen was the only manufacturer to achieve an A rating, meaning that its real-world NOx emissions are less than or equal to the Euro-6 limit recorded in the laboratory
The new Volkswagen Tiguan 2.0 diesel became the fifth VW model and eighth Volkswagen Group vehicle to be awarded an A rating since the EQUA Index was launched earlier this year.
In contrast, two new Renault models, the Espace 1.6 diesel and Megane 1.5 diesel, were both rated at the lowest, H grade, meaning that they emit more than 12 times as much NOx on the road as official tests suggest. Also falling short was Hyundai, with the i40 1.7 diesel and Santa Fe 2.2 diesel both emitting up to eight times the Euro-6 NOx limit on the road, achieving an F grade.
Nick Molden, CEO and founder of Emissions Analytics, said: “We continue to see a number of encouraging results from vehicle manufacturers such as Volkswagen, which show that a number of new diesel engines are as clean on the road as they are under official tests. However, there are still some new cars that are performing very differently in the real world to the laboratory.”