Euro 6 vehicles continue to deliver drastically different results when tested in the real world according to the latest additions to EQUA Air Quality Index.

With diesel vehicles continuing a recent trend, the new results show that it’s wrong for car buyers to assume all Euro 6 cars are equal in terms of producing harmful emissions when used in the real world.

The cleanest new machines include the BMW 520d auto and Mercedes C220d auto which produced NOX in line with official figures, while the BMW 216d Active Tourer recorded the second-highest band of pollution, equating to roughly eight-12 times the Euro 6 limit.

Petrol models performed far better, with all new models hitting the top mark for air quality - except one which was only one band adrift.

Nick Molden, CEO and founder of Emissions Analytics, said: “There’s no way of predicting how a car will perform, as engine size, badge or even type of car are no solid guide. This continuing variance between official and real-world figures not only means that car drivers remain in the dark, but any scheme using these official figures as a guide to help reduce air pollution is doomed to fail. We urge government and policy makers to consider real-world test results as critical in tackling the issues that can have a serious impact on health.”