Could there be another “Dieselgate” on the horizon? It could be, as new reports suggest that several carmakers, including Volkswagen, Daimler, and BMW colluded to fix the price of other diesel emission treatment systems.

Reuters, citing German publication Der Spiegel, reports that VW, BMW, Audi, Porsche, and Mercedes-Benz may have violated competition rules by discussing vehicle technology in industry groups for nearly 20 years.

According to documents viewed by Der Spiegel, about 200 employees of the carmakers began meeting in the 1990s to discuss topics such s technology, costs, suppliers, and emission strategies for diesel vehicles.

Beginning in 2006, the carmakers allegedly discussed the cost of AdBlue — a diesel engine exhaust emission treatment system — deciding to use smaller tanks in their vehicles.

It’s unclear if the alleged collusion could have influenced some of the carmakers’ choice to use so-called defeat devices to skirt emissions standards.

Volkswagen, which owns Audi and Porsche, previously admitted to using the devices in more than 11 million vehicles world-wide. Daimler and BMW have both denied allegations that they manipulated emissions tests for certain vehicles.

Germany’s Federal Cartel Office tells Bloomberg that it doesn’t comment on ongoing investigations, but confirmed that it had searched six car-industry companies in the past related to collusion concerns.

Each of the carmakers declined to provide comment to Reuters and Bloomberg on the matter. Consumerist has reached out to the companies. We’ll update this post if we hear back.

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.