Prius plugs in

JUST weeks after a United Auto Workers document revealed that General Motors would begin production of its Chevrolet Volt plug-in hybrid car in 2010, Toyota has moved to reassert its world hybrid leadership with a new research program in the US involving a plug-in version of its Prius.

The Japanese auto giant, which is striving to achieve one million annual hybrid sales worldwide by the time the Volt hits the showrooms, has developed two prototype vehicles with oversized packs of nickel-metal hydride (NiMh) batteries that simulate the level of performance the company expects to achieve when it develops more advanced, compact and powerful battery systems.

Toyota has confirmed in recent weeks that the third-generation Prius – due in 2009 and previewed at the Tokyo motor show last month by the 1/X concept – will continue with NiMh batteries rather than lithium-ion. Overseas reports also suggest that the new Prius will be bigger, much less expensive and that the range will include a station wagon from 2010/11. The latter was previewed by the Hybrid-X concept shown at the Geneva motor show in March.

Left: Prius plug-in, Hybrid-X and 1/X (bottom).

While company management has refused to specify a production timetable for plug-in versions, the prototypes delivered to the University of California (Berkeley and Irvine campuses) last week indicate that such derivatives are a development priority.

According to Toyota, the prototypes are designed to run in electric mode more often, and at higher speeds, than the current Prius – resulting in better fuel economy and reduced tailpipe emissions.

Reductions in CO2 emissions will vary depending on the source of the electricity that recharges the secondary battery. Charging takes up to four hours and is done with an ordinary three-prong cord and household electrical outlet. The extra (6.5Ah) battery is housed in the trunk, taking up what was space for a spare tyre.

Although the vehicle’s weight increases 100kg, the electric driving range increases to around 11km (with fully charged batteries). The non-plug-in Prius allows electric drive for brief periods, occasionally up to a few minutes at very low speeds.

“We feel there is tremendous promise in plug-in hybrids,” said Toyota Motor Sales USA group vice-president and general manager Bob Carter.

“However, there are still many questions to be answered and challenges to be resolved before Toyota can bring a product to market that has the quality, durability and reliability that customers expect from us.” The three-year program is being funded jointly with the California Air Resources Board and the California Energy Commission.

UC Irvine will focus on technical challenges and determine the emissions benefits of plug-ins. This will include how to measure and test fuel economy and vehicle emissions, how to account for the upstream emissions from electricity generation, and, in regions with a higher-carbon grid mix, whether plug-ins would provide an emissions benefit.

UC Berkeley will focus primarily on the customer experience. The latter will include whether consumers would want to plug in their vehicles in the first place, and the trade-off drivers are willing to make between range, charging time, battery size and battery costs.

Researchers will also look at when people will charge their batteries and whether they will want access to outlets where they work and shop.