The suit, filed in federal court in Detroit, is on behalf of more than 705,000 people who bought or leased Chevy "Duramax" Silverado and Sierra trucks between 2011 and 2016. It alleges that the company employed three different "defeat devices" to bypass state and federally mandated emissions tests and that these vehicles actually produce between two and five times the legal limit of NOx gas.

GM has denied the charges' validity, calling the lawsuit "baseless". A group of law firms, including Hagens Berman Sobol Shapiro (which was involved in the VW case), filed the suit.