![]() "The problem is that this number will be broadly discussed as a comparison to other cars, particularly the Prius. "So it isn't an 'untruth,' as long as the main thing you are concerned about is the burning of gasoline as a resource, as opposed to the actual energy efficiency of the system," Siry wrote of GM's 230 mpg claim. Trouble is, the resulting figure doesn't take into account various drive cycles or charging losses. To determine the MPG equivalent of an EV, Siry wrote, you can use the energy equivalent of a gallon of gas (33.7 kWh) to determine how far an electric vehicle would go on the same amount of energy. Darryl Siry, the former chief marketing officer at Tesla Motors and a a green tech consultant, wrote in his blog that when trying to determine "miles per gallon" for a an EV, "you end up in a very strange debate with very strange outcomes." Toyota is among the automakers developing plug-in hybrids, and the Japanese automaker says we'll see a plug-in Prius in 2012.īut at least one EV advocate says GM's claim is unrealistic. The standards are to be published later this year. The EPA draft that General Motors referred to repeatedly is SAE J1711 (.pdf), " Recommended Practice For Measuring The Exhaust Emissions And Fuel Economy Of Hybrid-Electric Vehicles." It will create uniform chassis dynamometer testing procedures for testing emissions and fuel economy. "But mpg is the only metric anyone understands." "It's difficult to translate electric car performance to miles per gallon," Bragman said. ![]() Henderson said the Volt will get 25 kilowatt-hours per 100 miles - but because that is essentially meaningless to anyone but an EV advocate, GM is touting the car's fuel efficiency instead. "It's still kind of fuzzy," Aaron Bragman, an analyst with IHS Global Insight who attended the briefing, told us when we asked how GM arrived at the 230 mpg figure. The EPA is working with the Society of Automotive Engineers to develop a methodology for calculating fuel economy ratings for EVs and plug-in hybrids. They have not been verified or certified by the EPA, which would not confirm GM's figure. Still, General Motor's claims are just that - claims. Henderson did not say what the Volt might achieve in highway driving, but he told reporters and analysts gathered for a briefing at GM's sprawling Technical Center in Warren, Michigan, he is confident the car will top 100 mpg.
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