As part of an ongoing assessment of the potential for reducing greenhouse emissions of light-duty vehicles, the U.S. Environmental Protection Agency (EPA) is adopting an updated methodology for applying the results of full vehicle simulations to the range of vehicles across the entire fleet. The key elements of the methodology update, responsive to stakeholder input, include greater transparency in the process used for determining the values of technology effectiveness that are used in EPA’s fleet compliance modeling with more direct incorporation of full vehicle simulation results. This paper begins by summarizing the methodology, presented more fully in a companion paper, for representing existing technology implementations using ALPHA full vehicle simulation for each vehicle in the baseline fleet. For future technologies, response surface equations (RSEs) are automatically generated from full factorial simulation of every conventional technology combination that will be considered. Because the regressions are not extended to represent technology combinations that were not actually simulated, these RSE’s produce emissions values with high fidelity to the ALPHA simulation results. From the vehicle baseline simulation results and the RSE for the appropriate vehicle class, the reduction in emissions can be determined for a future technology package considering the road load, power and performance, and technology implementations that are unique to a particular vehicle. This paper will also discuss modifications to the effectiveness assessment based on vehicle power/weight ratio and road load HP/weight ratio, as well as an examination of the effect of performance changes in the vehicles.