The European Commission has formally accused BMW, VW, and Daimler of colluding to impede the rollout of emissions limiting technology. These companies, whose car brands include Mercedes, Audi, Volkswagen, Porsche, and BMW, are said to have limited and delayed the use of tech that would have reduced the emissions of diesel and petrol cars.

The Statement of Objections issued today comes a year and a half after EU authorities first raided the offices of the three companies over reports of possible collusion. Earlier that year, Der Spiegel alleged that the German automakers met in secret working groups going back to the 1990s which attempted to collude on diesel emissions. Last year, the commission announced it was opening an in-depth investigation.

Compared to these initial reports, the EU Commission’s statement alleges that collusion took place over a much shorter period of time. It accuses the three companies of colluding over two systems. Between 2006 and 2014 it says they colluded to limit the use of “Adblue” in their selective catalytic reduction (SCR) systems for Diesel cars. It also says that between 2009 and 2014 they conspired to delay or even avoid releasing ‘otto’ particle filters (OPF) which reduce petrol emissions.

The EU’s Competition Commissioner, Margrethe Vestager, said that while collaboration to improve products is allowed, “EU competition rules do not allow [companies] to collude on exactly the opposite: not to improve their products, not to compete on quality.”

With this statement of objections now released, BMW, VW, and Daimler will have a chance to review the European Commission’s findings and respond to them before the authority comes to a final decision. As well as forcing companies to stop anti-competitive practices, the commission could also fine each up to 10 percent of its annual revenue, which could amount to billions of dollars in fines.