Plug-in hybrid electric vehicles excel on gas mileage, reduce emissions, SDG&E study confirms

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Denise King


San Diego Gas & Electric


(877) 866-2066


        SAN DIEGO, July 15, 2009 – Two years after unveiling San Diego’s first state-of the art plug-in hybrid vehicle, SDG&E said the third phase of its multi-year study reveals that plug-in hybrids offer significant improvements in gas mileage and reductions in emissions when compared with standard hybrid and gasoline vehicles.

        SDG&E tested the performance of two 2007-model standard hybrid vehicles and then converted them into plug-in hybrids, using a lithium-ion battery conversion kit.  In the most recent study, the prototype battery was replaced with a production-model battery.  The same pool of drivers was used during vehicle evaluation. 

        When compared with the standard hybrid, the plug-in hybrid at 68 miles per gallon (MPG), achieved a 58-percent increase in gas mileage, a 37-percent decrease in carbon dioxide (CO2) tailpipe emissions, and a 10-percent reduction in fuel costs.  When compared with a conventional gasoline-fueled vehicle that averages 22 MPG, the plug-in hybrid achieved a 68-percent reduction in tailpipe emissions and a 54-percent reduction in overall fuel costs.

        The study findings were announced as state regulators and utilities met in San Francisco to discuss the role of utilities in advancing the electric and natural gas vehicle marketplace and fueling infrastructure.

        Today, California’s electricity capacity could recharge as many as 4 million plug-in hybrids when charged during off-peak hours when electricity use is low.  The plug-in hybrid’s fuel-cost savings over traditional gasoline-powered vehicles would save these 4 million consumers approximately $4.2 billion a year at today’s average gasoline price of $3 per gallon when compared to 15 cents per kilowatt-hour of electricity for 14,400 miles driven annually.

        With SDG&E’s deployment of smart meter technology, the interface with these vehicles in the future will allow customers to schedule charging time and select the lowest rate for charging.

        SDG&E said the study results confirm the viability of electricity as a clean and low-cost transportation fuel and validate the increased efficiencies of plug-in hybrid technology.

        “California has the most aggressive greenhouse-gas reduction goals in the  nation, with nearly 40 percent of those emissions coming from transportation,” said Hal D. Snyder, vice president of customer solutions for SDG&E.  “Integrating clean transportation alternatives, like plug-in hybrid and all-electric vehicles, will be critical to achieving the state’s goals.  SDG&E will do its part to help ensure the San Diego region is “plug-in” ready when electric vehicles hit the road.”

        Original equipment manufacturer plug-in hybrids and all-electric vehicles are expected to be delivered to showroom floors across the nation in late 2010.  The efficiencies are expected to be higher than those demonstrated in SDG&E’s study.

        The converted plug-in hybrids recharge their batteries through a standard 110-volt household outlet and charge in five to six hours for a 5-kilowatt-hour lithium-ion battery.  In the future, plug-in electric vehicles will primarily charge off of 220-volt for faster charge time on larger batteries.  Gas mileage in the plug-in hybrids is greatly improved because the vehicles use electricity from the grid and can run in electric-mode longer and more often than standard hybrid cars. 

        SDG&E is part of a 48-utility coalition with the Electric Power Research Institute and General Motors to advance the deployment of plug-in hybrid electric vehicles.  The collaborative is working to accelerate large-scale deployment of plug-in hybrid electric vehicles and create a blueprint for an electric fuel infrastructure.  The collaborative also is addressing issues that ensure safe and convenient vehicle charging, public education, and public policy requirements to enable a smooth introduction of plug-in hybrid electric vehicles as a transportation alternative to conventional vehicles.

        SDG&E is supporting the San Diego region’s growing interest in a variety of safe, alternative electric and natural gas transportation technologies.  In March, SDG&E announced it would partner with Nissan Motor Co. to help develop the market for zero-emission electric vehicles and charging infrastructure in the San Diego region.  Under the partnership, SDG&&E is serving as the local San Diego coordinator to help assemble a critical mass of regional electric vehicle fleets that municipalities, universities, the military , the port, private fleets and others use daily.  The public-private collaborative is working to further develop and fine-tune the charging infrastructure, which is the critical link in making the vehicles commercially viable.

        To learn more about SDG&E’s Clean Transportation Program, visit

        SDG&E is a regulated public utility that provides safe and reliable energy service to 3.4 million consumers through 1.4 million electric meters and more than 840,000 natural gas meters in San Diego and southern Orange counties.  The utility’s area spans 4,100 square miles.  Exceptional customer service is a priority of SDG&E as it seeks to enhance the region’s quality of life.  SDG&E is a subsidiary of Sempra Energy (NYSE: SRE), a Fortune 500 energy services holding company based in San Diego.