
Toyota is charging ahead with its plans to expand the Prius range, with a  compact people-mover as one of its top priorities. Now in its final  stages of development, the Prius mini-minivan, dubbed Alpha, will be the  first vehicle in the Prius line to use lithium-ion batteries when it  debuts in March 2011. Just one-third the weight of the nickel-metal  hydride battery pack used in the current production Prius sedan, the new  lithium-ion batteries generate greater power and are already in use in  the 
prototype  Prius plug-in hybrid.
The Toyota Prius Alpha sits on the 
current  Prius sedan platform but gets an extra row of seats in the back,  turning it into a mini people-mover. Toyota settled on the Alpha name  because the new addition simply adds 'alpha' to the Prius equation. The  new Alpha's overall length will be stretched by about 300 mm (one foot)  in contrast to the Prius, while its wheelbase will be extended 20 mm  (just under an inch).
A five-seater version is also planned, but  this variant will incorporate nickel-hydride batteries to save cost,  according to one insider. That same source also tells us that Toyota are  bullish about pricing and will offer the Alpha seven-seater from 2.5  million yen, undercutting many of the current seven-seater minivans on  the market now.
Inheriting the Prius' 1.8-litre Atkinson-cycle  petrol engine and THSII hybrid system, the new model's gasoline engine  will generate 98 horsepower while the electric motor is expected to  produce 81 horses. The maximum combined power output will be 135  horsepower. Fuel economy will likely be slightly less than the current  Prius sedan's 50 mpg combined, due to the Alpha's extra size and weight.