The Center for Alternative Fuels, Engines and Emissions (CAFEE) at West Virginia University (WVU) was contracted by the International Council on Clean Transportation (ICCT) to conduct in-use testing of three light-duty diesel vehicles, using a portable emissions measurement system (PEMS), over a variety of pre-defined test routes exhibiting diverse driving conditions pertinent to major United States population centers located in the state of California. Additionally, one vehicle was operated over an extended distance of nearly 4000km predominantly composed of highway driving conditions between California and Washington State. Also, two out of the three test vehicles were selected for chassis dynamometer testing at California Air Resources Board’s (CARB) El Monte, CA vehicle certification test facility; however, a detailed discussion of these results is not part of this report.