A worker on the assembly line for the new Audi TT. Photo: Retuers/Laszlo Balogh

German automakers, including Volkswagen, Audi, Porsche, BMW and Daimler, met in secret to share technology, agree on component costs and choice of suppliers, according to a report released by German publication Der Spiegel over the weekend. Shares of the companies dropped on Friday after details of the allegations trickled out early, the Financial Times reports.

The most damning of the accusations concerns an alleged agreement that all of the makers would use a smaller, cheaper AdBlue urea solution tank, which would not sufficiently cleanse emissions.

The allegations threaten to broaden distrust of the German industry, following a revelation that Volkswagen was using illegal software to understate emissions in tests, which resulted in US$24 billion in penalties.

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