The diesel summit was convened to deal with the so-called diesel scandal and allegations concerning suspected collusion among German automakers, something which is currently being investigated by the European Commission.
On July 21, the Spiegel magazine reported that Volkswagen, Audi, Porsche, BMW, and Daimler, as well as other leading German automakers, coordinated their actions on designing diesel emissions treatment systems in diesel vehicles. The media added that the companies had colluded to rig the size of tanks for AdBlue liquid, making it smaller and ultimately preventing effective emission treatment.
The previous major scandal involving German automakers emerged in September 2015, when the US Environmental Protection Agency (EPA) accused the Volkswagen Group, which owns 19 car brands, including Audi and Mercedes-Benz, of using specific software to falsify emission test results for its diesel-engine vehicles. Thousands of diesel-engine Volkswagen vehicles manufactured between 2009 and 2015 were estimated to have been programmed to cheat emissions tests for nitrogen oxide. Volkswagen admitted that 11 million of its vehicles worldwide had been fitted with the test-cheating software.