DETROIT – Toyota Motor Corp. President Katsuaki Watanabe says a forthcoming Toyota-brand hybrid-electric vehicle will be larger than the Prius.

The Prius, Toyota’s only dedicated HEV, is classified by Ward's as an Upper Middle passenger vehicle, as is the Toyota Camry.

In a group interview with select media at the North American International Auto Show here, Watanabe says the new HEV likely will be assembled in Japan, but he is uncertain in which markets it will be sold in.

Toyota last year showed a hybrid sports-car concept, the FT-HS, at the Detroit show, and it has been rumored the vehicle will be built as a next-generation Supra.

Toyota’s U.S. executives have spoken openly about a future Toyota hybrid that favors performance, as well as a Lexus HEV that is more of a fuel-sipper.

“The next thing we’re looking at and talking to our customers about is, while there is certainly a role for a power hybrid in Lexus, there could also potentially be a market for mpg-based hybrids,” Bob Carter, then general manager-Lexus Div., told Ward's last February.

Toyota will debut its new hybrid, as well as a dedicated Lexus HEV, at the 2009 Detroit show.

Meanwhile, Watanabe says an expansion of Toyota’s joint venture with Panasonic EV Energy Co. Ltd. will result in an additional 100,000 nickel-metal hydride batteries for the next-generation Prius. Current capacity at the plant is 500,000 units annually.

He says this is separate from his earlier announcement here that the JV will add a dedicated lithium-ion battery assembly line for automobiles.

For the time being, the Li-ion batteries will be reserved for upcoming plug-in hybrid vehicles, Watanabe says, adding it still is unfeasible to offer Li-ions in mass quantities due to concerns about their stability under high-volume manufacturing conditions.

Watanabe earlier announced a timeline of 2010 for the introduction of Toyota plug-in hybrids, but now says he has challenged his engineers to meet the deadline early.

“Mr. Watanabe’s favorite phase is as 'soon as possible' or as 'early as possible',” says Masatami Takimoto, executive vice president-powertrain development and quality.

While Watanabe says Toyota is not in a race with General Motors Corp. to get a plug-in hybrid to market first, “We don’t want to be the loser in that competition.”

All auto makers should be trying to engineer vehicles that have less negative impact on the environment, he says.