A class-action lawsuit accuses General Motors of rigging emission-control systems on 2011?2016 Chevrolet Silverado HD and GMC Sierra HD pickups with GM’s Duramax turbo-diesel 6.6-liter V-8 engine. If the allegations are proved true, the environmental damage from these 705,000 trucks, which the lawsuit said emit two to five times the legal limit of nitrogen oxides (NOx) in typical driving conditions, could easily exceed that of Volkswagen’s emission-test-cheating TDI engines.
The complaint, which was filed in U.S. District Court for the Eastern District of Michigan, cites tailpipe emissions for nitrogen oxides (NOx) with these turbo-diesel 6.6-liter V-8 engines that are well beyond the legal limits. The document also frequently mentions Volkswagen and suggests that, to be brought within compliance, these GM trucks are likely to need modifications that could hinder performance as well as fuel economy. The suit claims that GM used at least three defeat-device tricks in these trucks. The automaker is alleged to have programmed the emissions software to relax or ?derate? its emission controls after five to eight minutes of steady highway driving?a use case that isn?t part of an emission test cycle. Such behavior would also likely extend the interval for adding urea-based diesel emissions fluid (DEF), which serves to reduce NOx in the exhaust stream. With second and third defeat-device software hoops, GM also reduced emission controls below an ambient temperature of...