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(Photo: Ruben de Rijcke https://commons.wikimedia.org/w/index.php?curid=8735834)

Automakers conceded that laboratory tests of exhaust emissions don't accurately reflect real driving conditions and called for the adoption of a new test regime.

Germany's Federal Motor Transport Authority (KBA) and the UK Department for Transport last week released reports showing that emissions from diesel cars are, in general, far higher than shown in the official tests.

"Both these announcements highlight the known differences between laboratory test cycles and real-life driving conditions," the European auto industry association (ACEA) said in a statement. It added that European carmakers have been advocating for years to update the current test cycle, which was designed in the 1980s.

Germany's KBA found in its study that almost all of the 53 domestic and foreign diesel models tested spewed out considerably more nitrogen oxide than was evident from the official tests. The agency used the so-called Real Driving Emissions (RDE) test for this. Europe-wide adoption of RDE is set to become law in 2017.

The UK test of 56 vehicles in Germany and 35 in the UK also found higher levels of NOx emissions in test track and real world driving conditions than in the laboratory.

The UK report, stressed, however, that automakers operated within the letter of the law when submitting their cars for testing. "Our tests publlished today have not detected evidence of manipulation of emissions lab tests as used by the VW Group by any other car manufacturer," UK Secretary of State for Transport Patrick McLoughlin said in a statement.

Germany's VDA, the country's auto industry association, also noted that the KBA found that "illegal manipulation of software to falsify laboratory tests has occurred only in the the one known case."

Volkswagen admitted last year that it had installed so-called defeat devices in 11 million vehicles. The software detects when a car is being tested and then instructs the engine to run more efficiently for the duration of the test.

The VDA said that automakers had complied with European testing standards, but it acknowleged that "it is understandable that large discrepancies between official values and real-world results cause frustration and irritation and that customers and legislators expect more reliable information."

VDA President Matthias Wissmann said the recent revelations don't discredit diesel engines, but he said it's important to get new cars with Euro 6 compliant diesel engines onto the market as quickly as possible . Said Wissmann: "There is no reason to turn one's back on the most advanced diesels."