German carmakers Volkswagen, Audi, Porsche, BMW, and Daimler secretly worked together from the 1990s onwards on issues including polluting emissions from diesel vehicles, news magazine Der Spiegel reported on July 21. Volkswagen, facing tens of billions of dollars in compensation and fines after admitting to cheating on diesel emissions in 2015, had reported the cartel to German competition authorities in a letter seen by the weekly, as did Mercedes-Benz maker Daimler. Such cooperation between all of the country’s large car manufacturers could have included “behavior infringing antitrust law”, according to the Volkswagen letter. A spokesman for Volkswagen -- which owns Audi and Porsche – said on July 21 that the group would not comment on “speculation and conjecture”. BMW and Daimler similarly declined to comment. A spokesman for Germany’s federal competition authority recalled that the authority raided six companies in June 2016 on suspicion of infringing competition law in steel purchases by car manufacturers and suppliers.