On February 12, 2003, the Transportation Committee of the Montana House of Representatives heard testimony on House Bill 502, which proposed that all diesel fuel sold for use in internal combustion engines contain at least 2 percent biodiesel fuel by volume. The bill was discussed but tabled by the committee because of “unanswered questions surrounding this relatively new technology.” Specific concerns included:• “the effects of biodiesel blends on engine performance – specifically fuel economy, torque, and power – as compared to diesel;• cold weather product storage and potential for gelling;• sulfur, carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxide (NOx), and other emissions; and• potential for engine damage.”The Montana Department of Transportation (MDT) was asked by the House Transportation Committee to initiate a research project focusing on the viability of using biodiesel as an alternative fuel in MDT’s vehicle fleet. To undertake this study, MDT implemented this project in two phases: first, a review of relevant literature regarding the performance of biodiesel in motor vehicles; and second, a test application using a B20 blend (20 percent oil seed-based biodiesel, 80 percent conventional diesel) in three MDT vehicles housed in Missoula and three housed in Havre.This document describes Phase 2 of the Evaluation of Biodiesel Fuel research project: the field test.