As EPA and the U.S. Department of Justice built their civil enforcement case against Volkswagen, the agencies turned to ERG to estimate the excess emissions caused by VW’s use of defeat devices to cheat on emissions tests. ERG designed a customized modeling approach, specific to the VW case, to estimate the excess nitrogen oxide (NOx) emissions from affected vehicles. ERG evaluated available dynamometer and on-road testing emissions data to develop these estimates. ERG applied this tool to estimate cumulative nationwide excess emissions for affected diesel vehicles, adjusting for vehicle deterioration and scrappage rates over time. EPA, the Department of Justice, and the California Air Resources Board used the modeling results as one input for the final settlement.
Learn how ERG can support state NOx emission reduction programs under the $2.7 billion VW Environmental Mitigation Trust.