by Irv Miller
You may have read a recent headline and story in Automotive News that suggested a Toyota spokesperson said that our U.S. plug-in hybrid (PHV) test vehicles have achieved, on average, about 65 mpg in testing. The interview took place at the North American International Auto Show in Detroit last month.
We believe there was a misunderstanding between the reporter and the spokesperson, who were also discussing Prius vehicles that had been converted to plug-ins by aftermarket companies and are currently being tested by private individuals, companies, utilities and so on. Many of these owners of converted PHVs have stated or publicly posted performance numbers in the 65 mpg range.
For the record, Toyota has only a small test fleet of PHVs in the U.S. and has never offered mileage estimates on PHV technology. These PHVs are being used for auto show displays, brief demonstrations and university studies. They are very early "converted" prototypes using double nickel-metal hydride batteries.
Although mileage data has been collected during demonstration events, it varies too widely to offer any indication of what to expect consistently. Most importantly, these vehicles are not representative of the lithium-ion-battery-powered next-generation Prius PHVs that will be delivered to lease-fleet customers later this year.
When asked about the mpg performance of PHVs – either lithium or nickel battery powered – we have consistently answered that we believe that PHV mileage will vary dramatically, depending on driving style and driving conditions . . . even more dramatically than with a conventional gas-electric hybrid. This is due to the added weight of a large battery that, once depleted by pure-electric drive, will contribute nothing until it is plugged in and re-charged.
We have also stated that it is too early to discuss anticipated mileage ranges based on early preliminary testing in Japan by Toyota Motor Corporation engineers.
We look forward to getting in-use driving feedback from the 150 lease-fleet customers who will receive our lithium battery-powered Prius PHVs early next year. We anticipate a wide range of fuel efficiency performance numbers. And we regret the misunderstanding that prompted this recent news story.
Originally published on the Toyota Open Road blog on Feb. 05, 2009.
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