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Hello -

Here is a timely article on the issue of plug-in hybrids :

The Truth About EPA City / Highway MPG Estimates - Feature - Auto Reviews - Car and Driver - August 2009

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How will the EPA measure the mileage of electric cars and plug-in hybrids? Particularly tricky are upcoming cars such as the Chevy Volt, which can travel a significant distance on electric-only power. If the EPA were to run its fuel-economy tests with a fully charged battery, the Volt would burn no gas at all. So would the miles per gallon on the city cycle read “infinite”? According to the EPA, a likely solution is to test this new breed of hybrid twice—once in electric-only mode and again with the battery drained and the gas engine providing electricity—and then combine the test results. But should the two tests simply be averaged? GM argues that most customers will plug in the car at night and therefore be running on batteries the majority of the time, so the results should reflect a significant portion of efficient, electric-only driving.
Pure electric cars, such as GM’s EV1 of the 1990s and, more currently, the Tesla Roadster, have fuel economy stated in units of kilowatt-hours (kWh) per 100 miles. For example, the Tesla gets 32 kWh per 100 miles city and 33 highway, but these figures are Greek to American car buyers accustomed to miles per gallon. Which is better, 100 mpg or 32 kWh/100 miles? Everyone involved, including the automakers, seems to agree that all cars, including electrics, need to be rated on a mpg-equivalent basis where, for example, the amount of energy used by an electric vehicle could be converted into a volume of gas with the same energy content. All window stickers would then contain mileage figures in mpg. The EPA is currently in long, soul-searching meetings to agree on a standard; a draft proposal should be submitted by year’s end. Whatever the specifics, GM expects the Volt to carry a fuel-economy rating of well over 100 mpg.
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