Toyota Prius MPV minivan on way

And it will come with a lithium-ion battery pack, a first for Toyota.

Toyota intends to turn Prius from a single car into a full line of vehicles, partly because of its future hybrid plans and partly because its research shows people around the world instantly associate the word Prius with hybrids. The first extension of brand Prius from today's five-door family hatch is an MPV, scheduled for a debut in March 2011 - most likely at the Geneva Motor Show in Europe.

It is a relatively straightforward move for a car being called the 'Alpha' in Japan. The MPV sits on the same mechanical platform as the current Prius in showrooms, but gets a body stretch for space for an extra row of seats in the back. It will be about 300 millimetres longer overall, with a wheelbase increased by 20 millimetres. The name is a similar stretch, since the car is a 'plus-Alpha' addition to the Prius.

The mechanical package will be inherited straight from the Prius, which means its 1.8-litre Atkinson-cycle petrol engine and THSII hybrid system. But it will lose out slightly to the regular car on fuel economy, thanks to its extra weight.

The Alpha’s biggest claim to fame is the MPV will employ lithium-ion batteries, replacing the current Prius’s nickel-metal hydride type. At just one-third the weight of the current battery pack, the new Li-ion batteries generate greater power and are already in use in the prototype Prius plug-in hybrid.

A five-seater version of the Alpha is also planned, but this vehicle will use the current nickel-hydride batteries to save cost, according to one Toyota insider. The same source tells Carsguide that Toyota is bullish about pricing and will take the Alpha seven-seater into showrooms with a price that undercuts many current MPV rivals, including the Honda Odyssey.