"Real world" tests for new cars will be in force next week, on Friday 1 September.
New models of diesel and petrol cars will now have to pass a strict assessment of emissions before they are deemed roadworthy, as the government takes action on air pollution.
Under the old test, vehicles were tested in the lab on a rolling road but now they will have a 90-minute real world driving test.
The move comes in advance of a change to rules in 2020 which will tighten the restrictions on nitrogen oxide. The UK government has also made a commitment to ban the sale of all new petrol and diesel cars from 2040.
Transport minister Paul Maynard said:
We are taking strong action to clean up our air and these tough new emissions standards will reduce dangerous pollutants.
This government has led the way in Europe pushing for on-road emissions tests, alongside a tough new laboratory test, to clean up air in our towns and cities.
This will ensure all vehicles meet rigorous standards when driven on our roads – and we are going even further tightening requirements again in 2020.
The reforms are aimed at addressing the disparity between lab emissions and real world emissions. The government’s diesel testing programme last year found that today’s Euro 6 diesel cars were emitting six times more nitrogen dioxide outside the lab than inside.
It is also hoped that the new requirements will avoid another Volkswagen style scandal by ensuring manufacturers cannot cheat the emissions test.
During the 90-minute test vehicles will have emissions testing equipment attached to the exhaust pipe, and they must pass before they are approved to go on sale in Britain. The vehicle will have to do roughly equal splits of town, countryside and motorway driving. The test will then be rolled out for all new cars on sale in Britain from 1 September 2019.