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Toyota Touts Parallel PHEVs vs. GM Series E-Flex/Volt
Sep 5, 2007 (From the CalCars-News archive)
This posting originally appeared at CalCars-News, our newsletter of breaking CalCars and plug-in hybrid news. View the original posting here.
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Not only do we now have an explicit carmaker PHEV "race to be first" -- we're also seeing an emerging competition over technical solutions. This development is unexpected and very positive!

Below, read part of a story on Green Car Congress about Toyota's first matchup of its hybrid design vs. that of the Volt. (It includes a drawing that helps explain parallel hybrids (engine and motor power the wheels) vs. series hybrids (motor powers wheels, engine recharges batteries).

Of the 30+ blog comments online, you'll get a great range of views (a few are off-topic or technically incorrect, but many are very useful). You'll see:

  • the suggestion that Toyota is responding defensively to all the attention the Volt is receiving by telling its shareholders/investors that it has the better system architecture...but even less of a timetable than GM;
  • sophisticated presentations of the pros and cons of both solutions;
  • acknowledgment that the technical superiority of each depends on driving patterns;
  • the self-evident but most important point that the comparisons are theoretical until they're in cars that people can try and buy!

Toyota Takes A Swipe at GM's E-Flex 4 September 2007­2007/­09/­toyota-takes-a-.html#more

GRAPHIC: Toyota's view of E-Flex (the EV-based PHV) series-hybrid approach versus Toyota's PHEV approach. Source: Toyota

Toyota Motor Corporation (TMC) is positioning its emerging approach to plug-in hybrid vehicles—based on augmenting the battery pack of a conventional hybrid and altering the operating strategy (earlier post)--as an approach superior to that of the series-hybrid architecture of GM's E-Flex systems (earlier post), as represented by the different versions of the Chevy Volt.

The rationale, outlined by Toyota Executive Vice President Kazuo Okamoto in a presentation on the company's technology strategies to investors in Tokyo on 3 Sep, is that once current parameters such as driving range, required battery size and charge time are factored in, the augmentation of the existing parallel-hybrid platform makes the most sense.

The prototype Toyota plug-in is based on a Prius with a 2.6kWh NiMH battery pack supporting an all-electric range of 13 km (8 miles). The gasoline (flex-fuel) version of the Chevy Volt, targeted for production in 2010, is spec'd to have a 16kWh li-ion battery pack that supports a 40-mile all-electric range.

The presentation, Challenges for Sustainable Mobility, outlined a number of Toyota technology efforts including advanced gasoline and diesel engine work and alternative fuels (biofuels, hydrogen and electricity).

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