Dear EarthTalk: Should we expect to see “plug-in” hybrid cars anytime soon? I’ve been hearing they are on the horizon but I wonder if that means in one year or 10.

-- Bill A., Stratford, CT

Gasoline-electric hybrids now, like Toyota’s popular Prius, don’t need to plug in—you just fill their tanks with gasoline and the battery keeps charged by the internal combustion engine and by energy generated from the wheels when braking (a feature known as “regenerative braking”). The battery then powers the electric motor when it is called into service during idling, backing-up, crawling in gridlock, maintaining speed while cruising, and for extra uphill power when needed. As such, the electric motor is essentially a back-up engine while the hybrid relies mainly on the gasoline engine.

Plug-in hybrids take the concept further by plugging into a regular electric outlet to enable the vehicle to operate solely on its electric motor for ranges of 40-50 miles or more on a single charge. This has profound implications for commuters who need only drive short distances to and from work every day and who may be able to do so solely on electric power. The gasoline engine then becomes the supplemental one for when the car needs to travel farther than the electric engine can take it.

According to researchers at the University of California Davis, the electricity cost for powering a plug-in hybrid is only about one-quarter of the cost of powering a like-sized gasoline vehicle. Other benefits include far fewer fill-ups at gas stations and the convenience of recharging at home.

Toyota, currently the world’s largest producer of hybrid vehicles by far thanks to the success of its Prius, announced that it expects to have a commercially viable plug-in hybrid available to consumers as early as 2010 and is now testing prototype versions of plug-in hybrids at two California universities.

Felix Kramer of the California Cars Initiative (CCI), a non-profit dedicated to promoting plug-ins, called Toyota’s announcement “stunning and very welcome,” and says that these vehicles will be the cleanest practical cars on the road in a world where gas stations dot just about every intersection. The promise of such cars, says CCI on its website, is that drivers will have a “cleaner, cheaper, quieter car for local travel, and the gas tank is always there should you need to drive longer distances.”

U.S. automakers are also jumping onto the plug-in bandwagon. General Motors says that it will have mass-market plug-in hybrids—modifications of its Saturn Vue and Chevrolet Volt—on the road by 2010. Ford has also developed a small fleet of plug-ins, but is not yet ready to offer them to the public. Fisker, a U.S. start-up focusing on the creation of high performance, energy efficient vehicles, plans to sell an $80,000 plug-in hybrid sports car by late 2009. Chrysler’s Sprinter van was the first plug-in from a major U.S. manufacturer, but it is only presently available to a limited number of institutions as a fleet vehicle.

Plug-ins have also caught on elsewhere. Chinese carmaker BYD plans to sell a plug-in hybrid sedan in the U.S. within five years. And Volkswagen hopes to have a plug-in hybrid Golf ready to roll by 2010.

CONTACTS: California Cars Initiative; BYD; General Motors; Fisker

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