The European Commission has fined German car manufacturers for forming a cartel. The fine of 875 million euros ($1 billion) has been imposed on BMW and Volkswagen group, which also includes Porsche and Audi.

Competition Commissioner Margrethe Vestager said the manufacturers had the technology to make cleaner diesels, but chose not to use it. As a result, the automakers have deprived people of the opportunity to buy cars that are cleaner and more efficient, Vestager says.

“We will not tolerate collusion between companies. Competition and innovation to reduce pollution from motor vehicles are essential to achieving our ambitious climate goals,” said Vestager cited by Reuters.

The largest part of the fine was handed to Volkswagen: 502 million euros. The company will discuss whether it will contest the financial penalty. BMW will be fined 373 million euros and let it be known that it will accept it.

Daimler (Mercedes) also participated, but will not be fined, because the company eventually reported on the cartel.