GM's Plug-In Hybrid

How super-hybrids could slash gas consumption and usher in a new era of transportation.

Last week General Motors (GM) gave a boost to plug-in hybrid vehicles. It announced a new gas-saving technology that could transform transportation and make renewable sources of electricity, such as wind and sun, more feasible.

GM recently announced that it plans to sell a plug-in hybrid version of the Saturn Vue. (The nonhybrid version is pictured here.) Credit: General Motors

At the Greater Los Angeles Auto Show, the automaker committed to manufacturing versions of its hybrid Saturn Vue SUV with a much larger battery pack that can be charged via an ordinary household socket. The increased size of the battery pack makes it possible to rely more on electric drive than current hybrid vehicles do, thereby saving much more gasoline. The actual rollout date will depend on the development of suitable battery technology, according to GM chairman and CEO Rick Wagoner.

With the announcement, GM joined other major automakers that are developing plug-in hybrid technology, including Ford, Daimler Chrysler, and Toyota. "We hope to have some products in the near future, but we're not prepared to say yet when that will be," says Bruce Brownlee, the senior executive administrator at Toyota Technical Center, in Gardena, CA. "The potential [of plug-in hybrids] is terrific." (None of these car companies have yet committed to widespread production of such a vehicle.)

The announcement marks a change in strategy for GM, which has previously focused on addressing environmental issues and high fuel prices by modifying existing vehicles to run on ethanol and by developing hydrogen fuel-cell vehicles. Although GM still plans to continue its fuel-cell program, the decision to produce plug-in hybrids represents a move toward a more evolutionary transition from internal combustion vehicles. "It's nice to see General Motors not just putting all their bets on hydrogen," says Jason Mark, vehicles director for the Union of Concerned Scientists, based in Cambridge, MA.

Plug-in hybrids, which use both an electric motor and a gasoline-powered internal combustion engine, have been hailed as a bridge technology that could make it possible to cut gasoline consumption in the short term; meanwhile, researchers will continue to work out the problems with all-electric vehicles, such as the high costs that make long-range battery-powered vehicles unaffordable. The most commonly described version of this technology would allow drivers to commute about 20 miles without using gasoline at all. But in reality, plug-in hybrids will likely use a blended strategy, relying on the gasoline engine to boost power for acceleration or for climbing hills even during the first 20 miles. This blended strategy would still mean that a typical commute would use almost no gasoline. "Having an internal combustion engine for passing or hill climbing is probably a prudent thing to do," says Thomas Keim, a principal research engineer at MIT. "But if you're traveling around town or just cruising on the highway, you can do both of those things from the battery."

Plug-in hybrids have an advantage over all-electric vehicles in that the battery would be the primary source of power only for relatively short distances, allowing for a much smaller and less expensive battery pack. Since short trips represent the majority of driving in the Unites States, the result would be a dramatic decrease in gasoline use. Electricity use would go up, but the price of powering a vehicle with electricity from the grid during off-peak hours would be the equivalent of gas for about 90 cents per gallon, says Terry Penney, a technology manager for advanced vehicle technologies at the National Renewable Energy Laboratory, in Golden, CO.