Toyota's Super Hybrid Vehicle is ready in 2010

Toyota Motor Corporation is pushing its engineers to develop a plug-in hybrid-electric vehicle with a lithium-ion battery before 2010, raising the stakes in a race with General Motors.

The company plans to introduce its own lithium-ion hybrid, the Chevrolet Volt, around 2010.

The contest would help reduce the “negative aspects” of automobiles, and ultimately help the environment.

On Sunday night, Toyota, the world’s largest producer of hybrid-electric vehicles, announced it would produce a plug-in hybrid vehicle equipped with a lithium-ion battery by 2010, for sale first to big commercial customers like corporations and government fleets.

Toyota’s best-selling hybrid, the Prius, runs on nickel-metal hydride batteries. Lithium-ion batteries, like those used to power digital cameras and other small electronic devices, can potentially hold a longer charge than nickel-metal hydride versions, but they are also more expensive.

The Volt is set to run on lithium-ion batteries. Last fall, G.M. announced that it would build the Volt in its assembly plant in Detroit in 2010, although executives have said production might start after that.

Plug-in hybrids differ from the current hybrid vehicles in that they can be recharged externally, from an ordinary power outlet. In a conventional hybrid, the battery is recharged from power generated by its wheels.

Toyota and Panasonic have a joint venture in Japan, called Panasonic Electric Vehicle Energy, that produces batteries for the Prius. Toyota said Sunday that the venture, 60 percent owned by Toyota and 40 percent by Panasonic, would add a separate line at its assembly plant to produce lithium-ion batteries.

Toyota also said Sunday it planned to develop a new hybrid-electric car specifically for its Lexus division as well as another new hybrid for the Toyota brand. It said it would unveil both at the 2009 Detroit show.

The Lexus version will be the first hybrid car developed specifically for the luxury division, which offers a hybrid engine as an option on several models, including the RX crossover vehicle and the LS luxury sedan.

Toyota planned to offer diesel engines for its Tundra pickup truck and the Sequoia sport utility vehicle “in the near future,” but was not more specific.

Some environmental groups have pushed for plug-in hybrids, called PHEVs, or plug-in hybrid electric vehicles, as a way to save on gasoline, thus curbing emissions.

But some experts say plug-ins may not be the ultimate answer to cutting pollution, if the electricity used to charge them comes from coal-fired power plants.

That is also a concern to Toyota, which has asked researchers to determine not only whether consumers would be willing to pay for a plug-in, but also the effect it would have on the environment, James Lentz, the president of Toyota Motor Sales, said in an interview Sunday.

Nonetheless, G.M., Toyota and Ford Motor, the world’s three biggest car companies, all are developing plug-in hybrid vehicles. Along with the Volt, G.M. has said it plans to produce a plug-in version of its Saturn Vue hybrid. Ford has not yet given details of its plug-in hybrid, which it first discussed in 2006.

Indeed, Toyota executives initially questioned the practicality of plug-in hybrids, saying consumers preferred the convenience of hybrids that did not have to be recharged. Toyota has sold more than one million hybrids worldwide, including more than 800,000 Prius cars.

But the automaker announced last July that it was testing plug-in hybrids on public roads in Japan. It also is testing them in France, Toyota officials said Sunday, and it has given prototype versions of plug-in hybrid vehicles to university researchers in California.

Even before those test results are in, however, Toyota has offered plug-in hybrid test drives to journalists in Japan, California and Detroit, where a small fleet bearing the words “Toyota Plug-In Hybrid” traveled city streets on Sunday.

This plug-in hybrid — a version of the Prius, and not the vehicle Toyota announced it would build — differs from the Prius in four ways. It has two nickel-metal hydride batteries under the floor of its trunk, instead the conventional Prius’s single battery.

Unlike the Prius, which has a single fuel-filler door on the left side of the car, the plug-in model has another door on the right hand side that opens to reveal an outlet for the electrical charger. One end of the charger looks like a small fuel nozzle; the other end is a conventional three-pronged plug.

Each charge, which takes about four hours, uses the equivalent of 2.7 kilowatt hours of electricity, said Jaycie Chitwood, a senior strategic planner in Toyota’s advanced technologies group.

Inside the car, there is a button with the letters “EV” inside an outline of a car. If the driver pushes the button, the car reverts to electric vehicle mode, meaning the Prius is powered completely by its two batteries.

In electric mode, the Prius gets 99.9 miles a gallon, according to a gauge on a screen in the middle of the dashboard.

But it cannot go very far: the plug-in hybrid’s two batteries hold enough power for only seven miles, said Saúl Ibarra, a product specialist with Toyota who worked on developing the Prius.

By contrast, G.M. claims that the Volt will be able to hold a charge equal to 40 miles, after a six-hour charge.

Still, the electric mode of the Toyota plug-in is enough to start the car and run it until the engine reaches the point where it needs to tap the gasoline engine. The plug-in Prius can stay in electric mode until 62 miles per hour, versus around 30 miles per hour for the conventional Prius, Mr. Ibarra said.

Despite its decision to step up its plug-in hybrid development, Toyota is not sure how much more consumers will want to pay for it, Mr. Lentz said. The Prius starts at $21,100. Some after-market companies are charging nearly that much to convert Prius models into plug-ins, he said.

Given that, it is more likely that Toyota would offer plug-in technology as an option on the Prius, at least in the short term, rather than switch all of its hybrids to plug-in models.

Ultimately, Toyota must determine “do people want to plug in their car?” Ms. Chitwood said.