The European Commission has launched an antitrust investigation into the Volkswagen Group, BMW and Daimler, over allegations they colluded to keep certain emissions control devices from reaching the market in Europe, according a statement the Commission released on Tuesday.

The technologies the group allegedly sought to bury include a selective catalytic reduction system for diesel vehicles, which would help to reduce environmentally problematic oxides of nitrogen in passenger cars, and "Otto" particulate filters that trap particulate matter from gasoline combustion engines.

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"The Commission is investigating whether BMW, Daimler and VW agreed not to compete against each other on the development and roll-out of important systems to reduce harmful emissions from petrol and diesel passenger cars," said Commissioner Margrethe Vestager, head of competition policy for the European Commission, in a statement. "These technologies aim at making passenger cars less damaging to the environment. If proven, this collusion may have denied consumers the opportunity to buy less polluting cars, despite the technology being available to the manufacturers."

The Circle of Five talked about a number of other subjects in its meetings, according to the statement by the European Commission. They included the maximum speed at which convertible tops should open and close as well as the speeds at which cruise control would work, so not all of its alleged activity was salacious and shady.

It's not totally clear what the penalties would be if the Circle of Five is found guilty of collusion, but we're betting it's not going to be good. If there is one thing the German car industry doesn't need, it's more emissions-related bad press.

Representatives from BMW, Daimler and the VW Group didn't immediately respond to requests for comment.