PLUG-IN CARS

Between the near-record price of crude oil and the warnings about the end of the petroleum age, it's a great time to be hawking hybrid cars.

Hybrid cars get their power from a regular gasoline engine and a battery-powered electric motor. By balancing the load on the engine and recovering energy otherwise lost in braking, hybrids can get sky-high mileage. Toyota's Prius, for example, gets 48 miles per gallon in the city, and 45 mpg on the highway, much better than the similar-sized Corolla (28/37 mpg).

From the standpoint of energy conservation or global warming, we do hope that cars with an electric boost may edge out three-ton, four-door, eight-cylinder pickups with gas mileage in the low teens....

Hybrids combine the reduced air pollution and higher efficiency of battery power with the longer range of a gasoline engine, producing a car that travels further on each unit of energy while reducing the use of fuel and the release of carbon dioxide, the primary greenhouse gas.

More than half a million hybrids are selling annually in the United States, and manufacturers are scrambling to join the hybrid herd. Whether their motivation is a desire to brag about high mileage or to bask in the glow of "hybrid chic," hybrids offer a quick route to reducing gasoline consumption, oil imports, and greenhouse-gas pollution.

The best is yet to come
But it turns out that today's hybrids are only a start: The next generation of "plug-in hybrids" promises much greater reductions in fuel consumption and pollution. These cars use a super-size battery to achieve much greater all-electric driving range.

While today's hybrids resemble conventional cars with a battery assist, the plug-in version is more like a battery car with gasoline assist. Like the battery car, the plug-in hybrid offers radical pollution reductions, but adds the critical advantage of unlimited range.

When the battery is charged from a regular electric outlet at night, it stores enough energy to drive 20, 30, even 40 miles. Even though batteries are heavy and expensive, a 30-mile battery could liberate most American commuters from gasoline, especially if the car is charged at work before the drive home.

Plug-in hybrids could make visits to the gas station a special occasion rather than a weekly misery.

At today's prices, energy will cost about one-third as much when electricity rather than gasoline is moving the car, so plug-in hybrids could reduce the cost of driving.

But the ultimate payoff of plug-in hybrids is this: By placing a big battery in millions of garages, they may open the door to a vast expansion in solar and wind electricity.

Plug in, turn on, drive off
No manufacturer yet makes a plug-in hybrid, although several firms do sell kits with a big battery and control unit that will convert an existing hybrid into a plug-in. A number of auto-bigs, including Toyota and GM, say they intend to release plug-in hybrids within a few years.

That announcement marks a fascinating about-face for Toyota, which has long emphasized that its Prius was not a battery car. "They worked a long time to explain that you don't have to plug these in," says Don Hillebrand, director of the Center for Transportation Research at Argonne National Laboratory. "I think that one thing that spooked Toyota [about introducing a plug-in hybrid], is that they had just got done with explaining that the Prius does not have a cord coming out of the tail."

The Why Files could not afford a plug-in hybrid, so we phoned Tom Paque, a vice-president of Wisconsin Public Power Inc., which converted two Priuses as corporate cars. "We get a lot of thumbs up," Paque told us. "I think in general people don't know much about plug-in hybrids, but I do believe they understand [the idea of] using electricity in cars, and are excited about it."

Aside from all the technical hurdles involved in producing long-lasting, powerful but affordable batteries, Paque says, "It's going to be a challenge, from the consumer perspective, to explain these. People have the assumption that battery-powered cars are slow, and have limited mileage.... This approach, adding an 'electric gas tank' to a hybrid, is a really cool incremental step."