In June 2005, the United States Environmental Protection Agency (USEPA) signed a final rule implementing in-use testing requirements for heavy-duty diesel (HDD) engines. The program requires manufacturers to measure gaseous and particulate matter (PM) exhaust emissions from diesel engines using portable emission measurement systems (PEMS) installed on vehicles. In order to measure PM emissions, a cooperative contract between Sensors, Inc. and the USEPA was commenced to develop a Proportional Particulate Mass Device (PPMD). It is comprised of three key elements: a micro-proportional sampling system (MPS) incorporating an exhaust flow-meter (EFM) and an eight element quartz-crystal microbalance (QCM) to measure particulate mass. Evaluation of the exhaust flow meter (EFM) at third-party facilities have shown that the mass emission data and flow data produced with the EFM correlates extremely well with traditional (non-portable) constant volume sampling (CVS) certification systems. A single element version of the QCM has been undergoing extensive testing in both CVS systems and in an on-board MPS based system. These tests include a 760 vehicle EPA sponsored emissions study in Kansas City and an on-board 5000 mile diesel truck study. Completing the list of key components of the PPMD is the MPS, of which the first unit was delivered to EPA in pre-production form in August 2005 for testing in HDD emission certification laboratories. This unit has subsequently been tested in a Coordinating Research Council (CRC) test project (E66) at Southwest Research Institute (SwRI) in San Antonio, Texas and during the aforementioned 5000 mile cross country road test. This document provides the results of the road trip from San Diego, CA to Ann Arbor, MI.