Diesel cars marketed as the ‘cleanest in history’ are still belching out more than four times the legal limit of harmful nitrogen oxide, an investigation has found.

A study of the newest models of the greenest Euro 6 diesel cars on sale across Europe by Greenpeace investigators found half of cars recently approved for sale would not be allowed on the market if tested today.

Although car manufacturers were ordered to clean up their emissions following the Volkswagen ‘dieselgate’ scandal in 2015, limits for nitrogen oxide did not come in until September last year.

When campaigners tested cars between April 2016 and September 2017 they found half emitted nitrogen oxide gas above the new legal limit of 168mg/km NOx.

The worst results were for the 1.6 litre Fiat Tipo, which recorded overall emissions of 561mg/km - 3.3 times the current legal limit - and 753mg/km in urban driving - 4.5 times the limit.

Other cars with poor results for emissions include the Renault Scenic Energy dCi 95 which was 2.4 times over the limit and Opel/Vauxhall’s 1.6l Crossland-X at 2.3 times the limit.

And because they were tested before the new limit came into effect, manufactures are able to label their cars as Euro6 - the greenest category.