Mercedes, Honda, Mazda and Mitsubishi become the latest manufacturers whose cars 'emit far more pollution on the road than they do in a lab' 

  • Diesel cars emitted an average of four times the legal limit for nitrogen oxide
  • Tests revealed some unnamed 4x4s pumped out as much as 20 times the limit
  • But there is no evidence of any illegal activity on behalf of the car giants
  • Meanwhile, Volkswagen is expected to start recalling cars in January

Mercedes-Benz, Honda, Mazda and Mitsubishi are producing cars which emit far more pollution on the road than they do in a lab, according to new tests.

The four car giants join Volkswagen on the growing list of companies whose diesel vehicles passed the EU's official regulatory test in a laboratory setting, but fail to meet them in realistic driving situations.

On average, Emissions Analytics found the diesel vehicles they tested were four times the legal limit for nitrogen oxide (NOx).  

Pollution: The four car giants join Volkswagen on the growing list of companies whose diesel vehicles passed the EU's official regulatory test, but fail to meet them in realistic driving situations

Pollution: The four car giants join Volkswagen on the growing list of companies whose diesel vehicles passed the EU's official regulatory test, but fail to meet them in realistic driving situations

According to the data, obtained by the Guardian, Honda models pumped out six times the limit, while other unnamed 4x4 models were releasing as much as 20 times the limit.

Nick Molden, of Emissions Analytics, told the Guardian the problems with VW diesel cars in the U.S. 'threw a light on a slightly different problem' in the EU - that of 'widespread legal over-emissions'.  

'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,' he said.

The problem seems to lie in the fact the cars were designed to perform better in the lab than on the road, but there is no evidence of illegal activity. 

The companies all told the Guardian they had done nothing wrong. 

Worldwide: Some 11million Volskwagens are affected by the scandal, which was revealed last month 

Worldwide: Some 11million Volskwagens are affected by the scandal, which was revealed last month 

Meanwhile, Volkswagen is expected to begin recalling millions of diesel vehicles in January to remove a device that is aimed at cheating emissions tests, and to bring them into compliance with anti-pollution rules in each affected country.

Some 11million cars are affected worldwide and the German auto giant is still drawing up a timetable for the massive repairs.

The car-maker has confirmed that nearly 1.2 million diesel vehicles in the UK are among those affected by the scandal.

The company has admitted to fitting the diesel vehicles with software that turns on emission controls when the car is being tested and then turns off when it is on the road.