Right now, the Prius plug-in hybrid vehicle (or PHV) is a prototype, and an experiment of sorts. About 150 PHV Priuses are running around the U.S. as part of a demonstration program. Toyota's goal is to collect data on how the cars perform so they can make adjustments if necessary before offering it to the general public for the 2012 model year . The only visual difference between the two cars is a little extra bright metallic trim, and a second fuel door mounted up front that hides the charging connector.
The mechanical differences are more significant. The PHV Prius uses all lithium-ion batteries (Li-ion), as opposed to the nickel-metal hydride batteries (Ni-Mh) of the standard Prius hybrid. Toyota says that's the plan for the foreseeable future, that the standard Prius will not get Li-ion batteries, at least not until it gets redesigned. The Li-ion battery pack in the PHV Prius is also much larger than in the standard car, and because Li-ion batteries have more energy density, the PHV Prius has more than twice the power output, giving the PHV Prius the ability to run longer and faster in EV mode. As long as you baby the accelerator, the PHV Prius can drive at speeds up to 60 mph in EV mode, but the gas engine will kick on under under hard acceleration. The Li-ion batteries in the PHV Prius charge quickly, in about three hours using a household-style 120-volt charger that Toyota will include with the car.
Among the trade-offs is weight, as the PHV Prius is carrying around about 300 pounds more batteries than a standard Prius. But those batteries gives the PHV Prius up to 13 miles of EV range, so the ill effects of those batteries on fuel economy can be negated depending on how a driver uses the PHV Prius. For short commutes and around town errands, the PHV Prius could deliver 70, 80 or even more miles per gallon since the gas engine only kicks in under heavy acceleration or after the 13 mile range is used up. However, longer, high-speed driving done mostly on the highway could bring the fuel efficiency down to the 50 mpg range like a standard Prius, or perhaps lower. Even with the pure EV range depleted, the PHV Prius will still work like a normal Prius, delivering low speed EV function and an electric boost to the gas engine under heavy acceleration, as well as the standard regenerative braking function. A separate Li-ion battery pack ensures the PHV Prius will continue to operate as a standard Prius even with all the plug-in energy depleted.
There are other trade-offs with the PHV Prius. The increased battery size means less cargo space, so the PHV Prius has no spare tire and the fuel tank is even smaller than the one in the standard Prius. Also, there are reports of the PHV Prius having a longer stopping distance than a typical Prius and during hard cornering and quick transitions, the extra weight is noticeable -- not that anyone is looking to autocross a Prius. Slightly more sluggish acceleration may result as well, but we'll have to wait until Toyota has a production version available before we can thoroughly assess such factors.
Toyota plans to price the PHV Prius under $30,000, and given the already substantial popularity of the Prius, the PHV version is likely to perpetuate Toyota's image as the go-to automaker for environmentally friendly transportation.
Check out Translogic 7.2 below. Bradley heads to Toyota's U.S.A. headquarters in Torrance, CA to test drive the plug-in hybrid Toyota Prius PHV.