Most new diesels are already achieving the more stringent RDE-2 emissions standards, which don’t come into effect until January 2020.

Data, released by the European Automobile Manufacturers’ Association (ACEA), shows that all of the latest diesel cars to be tested under the Euro 6d-Temp RDE type approval standards performed well below the required NOx threshold.

The current RDE test applies to all new car types since September 2017.

It measures key pollutants, such as NOx and particles, emitted by cars while driven on public roads over a wide range of conditions. RDE therefore ensures that pollutant emission levels measured during the laboratory test (WLTP) are confirmed on the road, and that the legal thresholds are not exceeded during day-to-day driving.

Each of the 270 RDE-compliant diesel vehicle types tested represents a whole ‘family’ of similar cars of differing variants, so a multitude of low-emitting diesel cars are now available on the market.

The German automobile club, ADAC, estimates that there are more than 1,200 different RDE-compliant cars available today.

Erik Jonnaert, ACEA secretary general, said: “These new findings prove that modern diesel cars, supported by fleet renewal policies and combined with alternative powertrains, will play a strong role in helping cities move towards compliance with air quality targets. In parallel, diesel vehicles will continue to remain important for reducing CO2 emissions in the short and medium term, even though all manufacturers are expanding their offer of electrically-chargeable cars.

“Auto makers have made major investments to quickly deliver these massive reductions in NOx emissions. It is important that we stop demonising diesel technology as a whole. Instead, we need to differentiate between the old diesel fleet and the latest generation of vehicles.”

ADAC recently performed independent on-road testing of RDE-compliant diesel vehicles and found that modern diesels emit 85% less NOx on average than Euro 5 cars, concluding that the latest diesels are “very clean”.

Additional testing demonstrated that the best-performing RDE-compliant Euro 6 diesels emit as much as 95-99% less NOx than Euro 5 vehicles.