Following a report last week that German automakers have been colluding on diesel technology, including fixing the size of Diesel Exhaust Fluid (DEF) tanks, since the 1990s, BMW said in a statement that it "categorically rejects accusations that Euro 6 diesel vehicles sold by the company do not provide adequate exhaust gas treatment due to AdBlue tanks that are too small."

"We compete to provide the best exhaust treatment systems," BMW said in the statement released over the weekend. "Unlike other manufacturers, BMW Group diesel vehicles employ a combination of various components to treat exhaust emissions. Vehicles which use urea injection with AdBlue (SCR) to treat exhaust emissions also employ a NOx-storage catalytic converter. With this combination of technologies, we fulfill all legal emissions requirements and also achieve a very good real-life emissions performance. This means there is no need to recall or upgrade the software of BMW Group Euro 6 diesel passenger cars."

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German magazine Der Spiegel first reported Friday that German authorities and the European Union were looking into possible collusion between German automakers, including BMW, Daimler, and Volkswagen Group, specifically the Audi and Porsche brands. The publication cited a July 2016 document from Volkswagen that said German automakers began meeting in the 1990s to synchronize on their technologies, costs, suppliers, and emissions control systems. One of the topics reportedly discussed over the course of the meetings was the size of DEF urea solution tanks, which Der Spiegel says were kept small to reduce costs. BMW maintains that its tanks are small because its vehicles consume less DEF than vehicles from other manufacturers, and says the talks with other automakers were in regards to tanking infrastructure in Europe.

Reuters reports Volkswagen has called a "crisis meeting" to discuss the allegations and the likely antitrust investigation that will follow. The German Cartel office raided the offices of six automakers and suppliers last year searching for evidence of steel price fixing. It could not confirm the existence of a follow-up investigation into technology, as such an investigation would be ongoing. In 2016, European truck makers MAN, Daimler, DAF, Iveco, and Volvo-Renault were revealed to be involved in a truck price fixing scandal. All except Volkswagen-owned MAN paid record fines, as VW was the one to bring the cartel to authorities' attention.

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There are conflicting reports regarding which automaker blew the whistle this time around, with Der Spiegel saying it was Volkswagen and Reuters claiming it was Daimler. Regardless of which company initially exposed the alleged cartel, German regulators are urging all manufacturers to come clean.