Volkswagen cars perform well in new NOx emissions tests

The majority of Volkswagen's latest petrol and diesel vehicles are clean when it comes to Nitrogen Oxide (NOx) emissions, according to new tests which measure the level of NOx being emitted in real-world driving conditions.

The new EQUA Air Quality Index, which allows car buyers to see how much NOx their cars produce in the real world, has revealed that many of the Volkswagen Group's newest cars – including the What Car? Car of the Year, the Audi A4 – are among the cleanest on sale today.

NOx emissions are harmful both to the environment and to our health and are the main cause of the smog we see in cities including London. The Air Quality Index carries out real-world testing on new cars, measuring the levels of NOx they produce and ranking them online. Cars that meet the latest emissions standards, Euro 6, are given a grade 'A' rating, while cars which produce far more than the legal limits are graded from B to H.

The first set of results, released today, contains the data for 400 cars, the majority of which feature older Euro 5 petrol and diesel engines, but the data also includes the results of more than 100 of the latest, Euro 6-engined cars. Among those models are some of the most popular cars in the UK, including the Ford Fiesta, Ford Focus, Vauxhall Corsa and Vauxhall Astra.

The launch of the Air Quality Index is particularly timely in the wake of the Volkswagen emissions scandal, which engulfed the motor industry late last year.

The full list of petrol-engined cars to receive an A rating is below:

• Audi A1, 1.4-litre engine with 123bhp
• Audi A3, 1.4-litre engine with 148bhp
• Audi A4, 2.0-litre engine with 187bhp
• Audi A5, 1.8-litre engine with 170bhp
• Audi RS3, 2.5-litre engine with 362bhp
• BMW 1-Series, 1.5-litre engine with 134bhp
• BMW X5, 4.4-litre engine with 575bhp
• BMW M3, 3.0-litre petrol with 425bhp
• Citroen C3, 1.2-litre engine with 109bhp
• Hyundai i120, 1.4-litre engine with 99bhp
• Hyundai i30, 1.6-litre engine with 183bhp
• Infiniti Q30, 1.6-litre engine with 120bhp
• Kia Sportage, 1.6-litre engine with 174bhp
• Mercedes-Benz CLA-Class, 1.6-litre engine with 120bhp
• Mercedes-Benz A-Class, 1.6-litre engine with 122bhp
• Mercedes-Benz B-Class, 2.0-litre engine with 184bhp
• Mini hatchback, 2.0-litre engine with 189bhp
• Mini convertible, 1.5-litre engine with 134bhp
• Seat Ibiza, 1.2-litre engine with 108bhp
• Seat Ibiza, 1.4-litre engine with 148bhp
• Seat Leon, 1.4-litre engine with 148bhp
• Seat Leon, 2.0-litre engine with 261bhp
• Seat Leon, 2.0-litre engine with 286bhp
• Smart Forfour, 0.9-litre engine with 89bhp
• Suzuki Celerio, 1.0-litre engine with 67bhp
• Vauxhall Astra, 1.4-litre engine with 148bhp
• Vauxhall Astra, 1.6-litre engine with 197bhp
• Vauxhall Corsa, 1.2-litre engine with 69bhp
• Vauxhall Corsa, 1.4-litre engine with 148bhp
• Vauxhall Corsa, 1.6-litre engine with 202bhp
• Vauxhall Viva, 1.0-litre engine with 75bhp
• Volkswagen Caddy, 1.4-litre engine with 123bhp
• Volkswagen Golf, 1.4-litre engine with 138bhp
• Volkswagen Golf, 1.4-litre engine with 123bhp
• Volkswagen Golf, 2.0-litre engine with 296bhp
• Volkswagen Golf, 1.0-litre engine with 115bhp
• Volkswagen Golf, 2.0-litre engine with 218bhp
• Volkswagen Polo, 1.2-litre engine with 89bhp
• Volvo V40, 2.0-litre engine with 242bhp

Diesel cars which have received an A rating:

• Audi A5, 2.0-litre engine with 161bhp
• BMW 3 Series, 2.0-litre engine with 184bhp
• Skoda Superb, 2.0-litre engine with 148bhp
• Volkswagen Golf SV, 2.0-litre engine with 148bhp
• Volkswagen Passat, 1.6-litre engine with 118bhp
• Volkswagen Scirocco, 2.0-litre engine with 148bhp
• Volkswagen Touran, 1.6-litre engine with 108bhp

Despite Volkswagen Group's success with these results, the lowest-rated Volkswagen car powered by a Euro 6 diesel engine - the Volkswagen Polo with an 89bhp 1.4-litre engine - received an F rating, indicating that it would not meet any former European emissions standards, and emits between six and eight times the amount of NOx allowable under today's Euro 6 standards.

Only three vehicles have received the lowest H rating in this first round of tests, indicating that they emit high levels of NOx - up to 12 times the legal limit:

• Fiat 500X, 1.6-litre diesel engine with 118bhp
• SsangYong Korando, 2.2-litre diesel engine with 176bhp
• Audi A8, 3.0-litre diesel engine with 247bhp

Like many other manufacturers, the Volkswagen Group's older Euro 5 vehicles received lower ratings, meaning they do not comply with any Euro standard and emit up to 12 times the legal limit of NOx. However, it is important to note that Euro 5 engines are no longer on sale in new cars.

While the new tool is being billed as good news for both car buyers and vehicle manufacturers by allowing a transparency of emissions data, several car makers have expressed concern at how the tests have been carried out. The Society of Motor Manufacturers and Traders (SMMT), which represents the views of the motor industry, has said it "can't comment on results from non-official tests where the robustness or methodology is unclear."

Nick Molden, the boss of Emissions Analytics, the firm which carried out the testing for the Air Quality Index, said: “The official European tests are now out of date, and produce results that aren’t realistic when compared to how cars are used in the real world.

"Recent revelations have also shown that it’s possible to exploit the tests, making a car appear far cleaner than it really is. The official tests only produce a pass or fail result. The EQUA Air Quality Index provides results on a scale, so it’s possible to see exactly how a car has fared in real-world driving.”

Molden also explained that the tool should help to restore the public's faith in diesel vehicles in the wake of the Volkswagen emissions scandal. "Drivers will be able to sort the dirty diesels from the clean diesels," he told What Car?.

"If you’re doing long-distance driving, you want to know that you’ve got a car which is reasonably clean. Dieselgate has meant that you’ve lost a bit of faith in diesels, and this allows you to buy a diesel with confidence. The aim is to help the car market."

To see the full list of results from the Air Quality Index, click here.

What is the Euro 6 emissions standard?

'Euro' standard is a set of European legislation for new vehicle emissions. The legislation begain in 1992 and set the limits for Nox emissions from new vehicles. Over the years, as different stages of Euro emissions standards have come in, the limits have become tighter. The previous Euro 5 standard, which came into force in 2009, allowed new petrol cars to emit 0.06g/km of NOx and diesel cars to emit 0.18g/km of NOx.

The current Euro 6 emissions standard, which came into force in 2014, allows petrol and diesel cars to emit 0.06g/km and 0.08g/km of NOx respectively.