The Specs on Toyota's Plug-in Prius

Here's the skinny on Toyota's plug-in version of the groundbreaking hybrid, its answer to GM's development of the electric Volt

by Ian Rowley

When General Motors (GM) showed off its Chevy Volt plug-in hybrid concept car at the North American International Auto Show in January, it achieved a rare public relations coup over Toyota (TM). After all, the Japanese auto dynamo has long grown accustomed to praise for its leadership in the hybrid segment and its unrivaled green image.

But this time around, GM won plaudits for signaling its interest in developing a plug-in electric vehicle that could be charged by a conventional power source at home as well as by the car's engine. That the Volt won't appear before 2010 at the earliest and faces important technical challenges didn't dampen interest. "It is a rare occurrence when Toyota gets 'out-greened' at a major auto show, or anywhere, for that matter. But GM has done just that with its Volt," the AutoExtremist.com blog noted at the time (see BusinessWeek.com, 1/19/07, "In the Green Push, GM Still lags Japan").

At a July 25 press conference in Tokyo, Toyota showed it won't be left behind in the race to take plug-in hybrids mainstream. Toyota announced that it has won approval from the Japanese government to begin testing a new, plug-in version of its current Prius hybrid vehicle on Japanese roads. Further tests will begin in the fall in the U.S. and Europe. "[The plug-in Prius] is effective at reducing carbon dioxide and conserving oil and air quality," Masatami Takimoto, an executive vice-president at Toyota, told reporters. "After reviewing the results, we plan to accelerate our plug-in hybrid plans."

Battery Hitch

The July 25 announcement means Toyota is the first Japanese automaker to win approval to test plug-in hybrids in Japan. Takimoto declined to say, though, how long it will take Toyota to get its plug-in Prius from the test stage to commercialization. He admitted that, like GM with the Volt, Toyota faces an obstacle in battery technology. The problem is that automakers need more powerful, lighter lithium-ion cells—variations of the kind used in cell phones and laptops—but to date no one seems to have found a way to mass-produce the cells for use in cars.

Speaking in February, Toyota chief Katsuaki Watanabe told BusinessWeek that the next-generation Prius, expected in late 2008 or early 2009, would use li-ions (see BusinessWeek.com, 3/5/07, "Toyota's Bid for a Better Battery"). But in recent months, Toyota appears to be having difficulties meeting that timeline.

Reports in Japan have noted that Toyota executives are concerned about safety, and that the next model upgrade of the Prius will use nickel metal hydride cells, at least initially. Executives, meanwhile, are reluctant to discuss the progress of li-ions. "This is a problem for Toyota. They still need more time to develop lithium-ion batteries," says Hirofumi Yokoi, an auto analyst at CSM Worldwide in Tokyo. "I don't know if GM will beat Toyota, but I'd guess it's pretty even right now."

No Space for a Spare Tire

All of which could explain why the test models of the plug-in Prius in Tokyo today all use nickel metal hydride cells like those used in current conventional hybrid models. From the outside, the plug-in version looks much the same as any other Prius. Indeed, only the paint job (which features a large, white plug and the words "plug-in hybrid" in large letters) makes it obvious that this isn't a conventional version of the best-selling hybrid.