The European Commission has launched a new investigation into the VW Group, BMW and Mercedes-Benz owner Daimler over suspicions the three vehicle manufacturers colluded to limit a roll-out of clean emissions control systems for their cars.
It's alleged the German brands were in cahoots to prevent competing with each other to develop and introduce two emissions technologies that are designed to reduce harmful pollutants from vehicles.
The in-depth investigation by the competition commission will aim to establish if the three breached EU anti-trust rules that prohibit cartels and restrictive business practices.
The two emissions systems brought into question are selective catalytic reduction systems (SCR) and 'Otto' particulate filters (OPF).
SCR reduces the level of harmful nitrogen oxide emissions from diesel vehicles, while OPF cuts down particulate matter from petrol-powered machinery.
Both have been linked to the onset of premature deaths and health issues.