Five leading car manufacturers are facing trial in the United Kingdom over the “dieselgate” scandal

The High Court is hearing a class action lawsuit representing 850,000 drivers, according to Skynews.

A decade has passed since dieselgate first emerged.

The scandal initially hit the Volkswagen Group, eventually costing the company roughly £30 billion in fines and compensation.

In 2015, it emerged that the German automaker had installed so-called “defeat devices” in most of its diesel models—software designed to produce falsely low emissions readings during official tests.

The majority of VW’s financial penalties were in the United States, where it was found that the vehicles were emitting up to 40 times the legal limit of nitrogen dioxide under normal driving conditions.

Owners of diesel vehicles from Mercedes-Benz, Ford, Nissan, Renault, Peugeot, and Citroën allege that, like Volkswagen, these manufacturers installed illegal software to make emissions appear compliant during testing.

They contend that emissions far exceeded legal limits during regular on-road driving.

The trial will examine a limited selection of diesel models from the five manufacturers.

Leigh Day, one of the lead law firms representing the claimants, describes the class action as unprecedented in scale for England and Wales. If extended to the 14 brands it alleges manipulated testing, the case could eventually involve up to 1.8 million people.