EPA and NHTSA are sponsoring a technical workshop on December 10 and 11, 2014, at Southwest Research Institute (SwRI) in San Antonio, Texas. SwRI researchers will present technical work completed under the direction of EPA and NHTSA to assist in developing Phase 2 medium- and heavy-duty GHG and fuel efficiency standards. This technical work includes testing conducted over-the-road and on heavy-duty chassis dynamometers, powertrain test cells, and engine test cells. This work has been conducted to advance test procedure development and validate refinements that agencies have been considering for the greenhouse gas emissions model (GEM) used for heavy-duty vehicle certification. Aerodynamic tractor testing via both coast-down and constant-speed test procedures will also be presented, in addition to results from recent heavy-duty engine and vehicle technology modeling. SwRI will also describe simulation studies to look at the potential fuel saving performance of numerous MD/HD engine and vehicle technologies. This workshop will not include discussion of policy considerations such as Phase 2 program stringency or program structure. Rather, this workshop is an opportunity for interested stakeholders and individuals to learn more about recent EPA and NHTSA sponsored technical research, to engage directly with the SwRI researchers who have been conducting this work, and to provide initial feedback on work conducted to date. All interested parties are welcome to attend. See http://epa.gov/otaq/climate/regs-heavy-duty.htm for the agenda, schedule, and information regarding online registration. There is no registration fee.