Four more brands have had their diesel emissions made public, revealing they produce more pollution on the road than in test conditions.

Certain Mercedes Benz, Honda, Mazda and Mitsubishi models emit levels of NOx (nitrogen oxides) in real driving conditions above the legal limit in the EU’s official laboratory test, the NEDC.

No evidence has emerged to suggest the brands used cheat devices like the ones fitted in Volkswagen cars, according to The Guardian.

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As the cars passed the NEDC test, they are not technically breaking the law, although many are calling for reforms of the NEDC.

The Mercedes diesel cars emitted an average of more than twice the levels of pollution produced in test conditions, while Honda’s diesel cars emitted between 3.6 and six times the limit.

Company Emissions Analytics tested 200 diesel cars and found just five to meet the regulatory limits in real-life conditions.

“The VW issue in the US was purely the trigger which threw light on a slightly different problem in the EU – widespread legal over-emissions,” Emissions Analytics head Nick Molden told The Guardian.

“For NOx, [diesel] cars are on average four times over the legal limit, because of the lenient nature of the test cycle in the EU.”

Two car makers, Mercedes Benz and Holden said they supported a reform of the NEDC test, which was failing to bring down the toxic levels of pollution in the air.

Inhalation of nitrous oxides can aggravate respiratory conditions and existing heart disease, and also can harm lung tissue.

Volkswagen is still assessing the damages of its emissions scandal, and may be dealt up to $25 billion in fines from US regulators alone.

Defeat devices were found to present in Volkswagen, Audi A3 and Skoda models.