Volvo have done it before in 1998. Seven manufacturers, Caterpillar, Cummins, Detroit Diesel, Mack Trucks, Navistar International, Renault Trucks, and Volvo Trucks. The trucks used engine ECU software to engage pollution controls during the 20-minute lab tests to verify compliance with the Clean Air Act, but then disable the emissions controls during normal highway cruising, emitting up to three times the maximum allowed NOx pollution. I wouldn't be surprised if they have done it again.
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