STI has worked with EPA and U.S. DOJ on multiple cases related to motor vehicle “defeat devices” that improve in-use fuel economy while detecting and passing emissions tests, leading to higher pollutant levels. STI’s first work in this area dates to the late 1990’s, when we worked with EPA to assess emissions impacts from the use of defeat devices on heavy-duty diesel engines. Seven U.S. engine manufacturers settled the enforcement actions by paying substantial fines and devoting resources to approved environmental projects.