Policy paper

Vehicle emissions testing programme: data and conclusions

The conclusions of our investigation into whether vehicle manufacturers are manipulating emissions tests, plus our testing results of real world diesel emissions.

Documents

Vehicle emissions testing programme (web version)

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Vehicle emissions testing programme (print version)

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Vehicle emissions testing programme: correction slip

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Vehicle emissions testing programme data

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Euro 5 vehicle data

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Euro 6 vehicle data

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Details

We established this important programme following the revelations that Volkswagen had been using software in their cars which caused the engines to behave differently during emissions tests, compared to real world driving. Not only has this caused disruption and distress to the 1.2 million Volkswagen users in the UK, it showed a lack of regard for the serious health consequences of nitrogen oxides (NOₓ) emissions and caused significant damage to the trust consumers have placed in car manufacturers across the country. It was vital that we immediately started an investigation into whether other manufacturers were using equivalent prohibited devices and more broadly to better understand why emissions results in the real world were significantly different from those tested under laboratory conditions.

Our testing programme was designed to test a range of the best-selling passenger diesel cars. We selected an independent and representative sample of vehicles to test in a variety of conditions using the latest technology. We appointed Professor Ricardo Martinez-Botas, Professor at Imperial College London, to provide independent academic oversight of the work.

Importantly, the tests have not detected evidence of test cycle manipulation strategies as used by the Volkswagen Group. However, tests have found higher levels of NOₓ emissions in test track and real world driving conditions than in the laboratory for all manufacturers’ vehicles, with results varying significantly between different makes and models.

Existing laboratory tests designed to ensure emission limits are met have been shown to be inadequate. However we have already secured a tough new ‘real driving emissions’ test in EU legislation. From next year, vehicles will have to meet emissions limits in real driving conditions across a wide range of typical operating temperatures. This will improve consumer confidence in manufacturers and deliver real improvements for our air quality. The results from our testing programme further confirm that the UK was right to push for the early introduction of these tough new limits.

Even before the introduction of the new limits, we are urging manufacturers to introduce new technologies to reduce emissions sooner than the new EU regulations require. Some manufacturers have announced that they intend to make changes to vehicles already in use, to improve emissions, and will offer this to customers on a voluntary basis. We welcome this and encourage action from other manufacturers.

We are committed to improving air quality. This research provides a valuable insight into diesel car emissions on our roads. Across the UK, the improvements being made to the testing of new vehicles will help reduce emissions and improve air quality. We will continue working to ensure that the new rules for real driving emissions and type approval are robust, deliver the expected outcomes and that manufacturers behave consistently.

Published 21 April 2016
Last updated 7 July 2016 + show all updates
  1. Vehicle emissions testing programme data.
  2. First published.