With the success of Hybrid Electric Vehicles (HEVs) in the automobile market, Plug-In Hybrid Electric Vehicles (PHEVs) are emerging as the next evolution of this attractive alternative. PHEV market penetration is expected to lead to lower gasoline consumption and less emission. The main objective of this project is to assess PHEVs’ emission reduction and energy profile impacts based on simulation of vehicles used to in activity and travel patterns drawn from the 2000-2001 California Statewide Household Travel Survey. Simulations replicating reported continuous one day data will be used to generate realistic emissions and energy impact assessment of PHEV market penetration. A secondary objective is to estimate the decreased gasoline consumption and increased electricity demand in California. This will involve testing various electric pricing strategies designed to mitigate the recharging demands placed on the grid during periods of peak consumption. This assessment of emission and energy requirements of PHEVs will provide a benchmark that will assist in determining the impacts of future PHEV penetration into the automobile market. Specifically, the study will provide an upper bound on the potential demand on the existing grid, as well as categorize expected energy and emissions impacts by time of day and source.