Latest real-world test data from Euro 6 cars added to the EQUA Air Quality (Aq) Index shows that it’s wrong for car buyers to assume that two-wheel-drive vehicles are cleaner than four-wheel drives.

Comparing two and four-wheel-drive test results reveals that the more capable models produce less nitrogen oxides when compared through real, on-road driving.

Concentrating on the latest Euro 6 compliant vehicles, the database, compiled by independent testers Emissions Analytics, shows the vast improvements that some manufacturers have made in helping cut harmful tailpipe emissions when developing new cars.

In total, 48% of the four-wheel-drive models tested fell in the lower EQUA Ag A-C rating, compared to just 28% of two-wheel drives. In addition, a total of 14% of Euro 6 compliant four-wheel-drive vehicles were clean enough to receive the EQUA Aq A grade, compared to 10% of two-wheel drives.

Of the 4x4s recently rated, the Audi Q2 2.0TDI Quattro, Porsche Panamera 4.0 V8 and VW Tiguan 2.0 TDi 4Motion all received EQUA Aq A grades. The new results also reflect some of the trends seen in recent EQUA test data, and indicate that cubic capacity is no guide to finding the cleanest cars. The average engine size of cars receiving an A rating is the same as those with the lowest H rating.

Nick Molden, CEO and founder of Emissions Analytics, said: “These latest results are very encouraging, and show that it really is possible for large, four-wheel-drive vehicles to top the tables for low emissions. Cars, like the latest Porsche Panamera, are now among the best – which is a huge achievement when you consider that the comparable model or the previous generation Panamera was rated under the lowest grade. This underlines that, with the proper development work, all cars can cut harmful NOX emissions.”

Independently financed and implemented the EQUA Index is designed to help end the confusion that many consumers face when trying to understand the complex subject of fuel economy and tailpipe emissions, with ratings openly published and freely available to all. 

The EQUA Index is totally independent of car manufacturers, trade associations and government. EQUA is a scientific undertaking, providing highly accurate information, obtained though standardised and repeatable testing conducted on real roads.

Reporting on four main areas, The EQUA Index covers fuel consumption, carbon dioxide, carbon monoxide and nitrogen oxides with easy to understand ratings available for over 60,000 vehicles. This free and powerful service provides a complementary suite of information covering the most important aspects of vehicle emissions.

The EQUA Index delivers drastically more realistic figures than the new official fuel economy test, the World harmonised Light vehicle Test Procedure (WLTP), set for introduction in 2017, which will still rely on laboratory-based testing.