Mexico is planning to revise its existing emissions standards for diesel heavy-duty vehicles (HDVs). The existing regulation, Norma Oficial Mexicana 044 (NOM 044), requires new vehicles to meet either U.S. Environmental Protection Agency (EPA) 2004 or Euro IV standards. Revisions to NOM 044 standards will require manufacturers of new heavy-duty vehicles to move directly to either EPA 2010 or Euro VI standards, skipping over any interim steps. The implementation of these vehicle standards will be coordinated with the nationwide availability of ultralow-sulfur diesel (ULSD) with fewer than 15 parts per million (ppm) sulfur, which is anticipated to be achieved under a separate regulation by October 2017. The purpose of this paper is to report on the results, methods, and underlying assumptions of a cost-benefit analysis that the ICCT conducted to support the decision-making process for updating NOM 044. The results of this analysis, as well as other technical considerations (e.g., equivalency of EPA 2010 and Euro VI standards) are summarized in the ICCT working paper Revising Mexico’s NOM 044 standards: Considerations for decision-making (Blumberg et al., 2014).