Question to the Department for Transport:

To ask Her Majesty’s Government what assessment they have made of the accuracy of laboratory tests on pre-production cars of air pollutants emitted from vehicles; and what plans they have to enhance the accuracy of such testing.

The Department for Transport conducted a Vehicle Emissions Testing programme the results of which were published in April 2016. This involved testing production vehicles on the legislated laboratory test, but also on a range of additional tests including measuring air pollutant emissions during real driving on public roads. Large differences were found when compared to type approval tests on pre-production cars. The government has been at the forefront of action at European level to introduce the new Worldwide harmonised Light-Duty Test Procedure (WLTP) which comes into force from September 2017 and is expected to significantly improve the accuracy and representativeness of laboratory type approval tests.