Which? emissions testing reveals huge car industry variation

New Which? diesel emissions testing reveals that Renault and Jeep were among the biggest air polluters for NOx of the carmakers it tested, with huge variations across the industry.

Which? analysed 278 diesel cars from leading global car manufacturers between 2012 and 2016, testing average NOx emissions alongside official Euro 5 and more recent Euro 6 limits – which are set at 0.18g/km and 0.08g/km respectively.

The tests also found:

  • All 16 diesel Renault cars tested had NOx emissions that were up to four times higher for Euro 5 and nine times above Euro 6 limits – 0.73g/km and 0.72g/km respectively.
  • The six Nissan cars Which? tested with Euro 5 diesel engines – a brand that Renault partners with – had average NOx emissions of 0.8g/km.
  • Jeep also produced some of the highest emissions – the two Euro 5 cars tested managed to emit, on average, 1.735g/km of NOx, which is nine-and-a-half times the Euro 5 limit they met in official tests.
  • The 33 BMW and BMW-owned Mini cars Which? tested had some of the lowest NOx emissions for diesel cars. Averages for BMW were 0.41g/km from Euro 5 cars and 0.14g/km from Euro 6 cars.

Despite high emissions rates among some car manufacturers, modern diesel cars are, on balance, cleaner than ever. However, despite universal limits, diesel cars from some carmakers continue to pollute significantly more than other brands in Which? tests.

New official tests to access car performance are due to be introduced from September 2017. For more information on car emissions, visit Which? Cars.

Richard Headland, Which? magazine editor, said:

“While our tests show that some car manufacturers are making progress on reducing the amount of toxic emissions from their models, many have a long way to go in cleaning up their act.

“We hope that the improved official tests being brought in later this year will more clearly name and shame those manufacturers that are failing to meet their obligation to lower emissions.”

Notes to Editors

  1. Which? car testing: Which? has tested more than 540 cars available in the UK and Europe between 2012 and 2016, 278 of which are diesel cars. Which? emission and MPG tests aim to be more realistic than the official tests. We aim to test cars as consumers would use them, making use of the WLTP cycle and our own motorway cycle. For more information on our tests and how they differ from official EC tests, go to: http://www.which.co.uk/reviews/cars/article/how-we-test-mpg-and-emissions
  2. Euro emissions limits: Euro 5 and 6 limits for diesel NOX are 0.18g/km and 0.08g/km respectively. If a car produces NOx or any other pollutant in greater numbers than the corresponding Euro 3 limit when in Which? tests, it cannot be a Which? Best Buy.
  3. Which? Cars: For more information on car emissions, visit which.co.uk/car-emissions
  4. VW tests: Which? has tested averages for VW Group cars (VW, Audi, Seat and Skoda), and they are some of lowest measured NOx averages. However, the Euro 5 diesel cars tested are part of the ongoing VW emissions investigation, and so a question mark remains over the results from these cars.
  5. Renault Response: All Renault vehicles conform to the current standards.  Since mid-2015, Groupe Renault has committed to improve the performance of its anti-pollution systems. The vehicles tested by Which? would not have benefited from this improvement plan. Groupe Renault fully supports the new standards coming in to practice from September this year.
  6. Nissan Response: We are committed to upholding the law and meeting regulations in every market where we operate. Specifically in Europe, all our vehicles sold in Europe meet the Euro 5/6 emission standards. This report, which looks at the variation between lab and ‘real world’ conditions, shows significant variances for most brands tested. We strongly support the new Real Driving Emissions (RDE) tests that will be implemented later this year and we will continue to develop innovative solutions to reduce our impact on the environment.
  7. Jeep failed to provide a response to the research.
  8. Tables – hi-res image available on request

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