Diesel cars produce more than double the amount of nitrogen oxide than trucks, new research based on real-world testing has found.

A report by the International Council on Clean Transport (ICCT) found that while the market’s newest HGVs (and buses) produce an average of 210mg/km of NOx, the newest diesel cars produce 500mg/km.

The report was an analysis of data from vehicles tested in both Germany and Finland.

The differences in emissions, said the ICCT, was partly because of the different, stricter tests the heavier vehicles are subject to.

HGVs, the report said, are given a high load test, a mobile testing device, or portable emissions measurement system (PEMS) test, and an off-cycle test, none of which cars have to undergo under EU law.

The report argued that cars should be given the same tests, and in September they will be required to be tested in real-world conditions with a PEMs device.

However the ICCT’s report said that even with planned changes, regulations on car testing will not be as stringent as those on HGVs by 2019.