Photo: GM

A class-action lawsuit filed on Thursday accuses General Motors of installing defeat devices in more than 700,000 trucks to beat emissions tests in the U.S., the latest in a string of diesel cheating allegations against automakers.


The 191-page complaint—filed on behalf of more than 705,000 people who own or lease GM Duramax diesel trucks—claimed the automaker installed at least three defeat devices in Sierra and Silverado heavy-duty trucks from 2011-2016. Comparatively, Volkswagen admitted to installing a device to skirt emissions tests on roughly 550,000 vehicles in the U.S., which sparked the so-called Dieselgate scandal in 2015 that has ever since increased attention on diesel emissions across the world.


GM said the suit was meritless.

“These claims are baseless and we will vigorously defend ourselves,” GM said in a statement. “The Duramax Diesel Chevrolet Silverado and GMC Sierra comply with all U.S. EPA and CARB emissions regulations.”

Defeat devices—known formally as an Auxiliary Emissions Control Device—reduces the effectiveness of emissions equipment while driving, but they’re legal as long as they’re used for specific reasons. But the suit says plaintiffs conducted a test of GM’s trucks and found they emitted two to nearly six times the legal limit.

“Its top selling Silverado and Sierra 2500HD vehicles emit far more pollution on the road than in the emission certification testing environment, and these vehicles exceed federal and state emission standards and employ at least three different ‘defeat devices’ to turn down the emissions controls when the vehicle senses that it is not in the certification test cycle,” the complaint says.


The suit also names German auto supplier Bosch as a defendant. Bosch was cited just this week in a lawsuit filed by the U.S. government against Fiat Chrysler over alleged diesel cheats, and the supplier was previously implicated in Dieselgate for allegedly helping develop VW’s defeat device.

A Bosch spokesperson said it takes allegations of diesel software manipulation “very seriously.”


“Bosch is cooperating with the continuing investigations in various jurisdictions, and is defending its interests in the litigation,” the spokesperson said. “As a matter of policy, and due to the sensitive legal nature of these matters, Bosch will not comment further concerning matters under investigation and in litigation.”

While several automakers have been accused of using illegal defeat devices since the Dieselgate scandal emerged in 2015, the scale of what’s covered in the complaint is significant. The VW scheme, for instance, has cost the German automaker nearly $25 billion in fines and led to criminal charges being filed against numerous individuals.


You can read the entire complaint below.