By Toyota's own admission, the Prius name is a bigger brand in terms of green credentials than the company itself, so expanding the Prius range is the sensible thing to do.
Toyota has spotted a gap in the European market for a seven-seat, sub-100g/km car, particularly for fleet buyers like car hire companies, and the Prius+ is its attempt to fill it. The lower of the two available trim levels, T4, sits at 96g/km and is expected to take around 70 per cent of sales ahead of the 101g/km T Spirit.
Even though it works in exactly the same way, the new model doesn't quite use the same Hybrid Synergy Drive system as the common-or-garden five-seat Prius, because in the latter the under-boot nickel metal hydride (NiMH) battery pack raises the load bay and means a third row of seats is not an option.
For the Prius+, the new and impressively compact lithium-ion (li-ion) battery has been cleverly sited in the centre console in the cabin, beneath the arm rest. The boot floor has been lowered and a third row of seats added.
Of course, the roof line has been raised while trying to maintain a recognisably Prius shape, and there's no doubting the practicality on offer.
The middle row of three individual seats (specifically for Europe) move forward and back independently, firstly so that each of the three occupants can get more shoulder room, but also so the available space can be balanced between the two rows of rear seats.
The upshot is that, believe it or not, you can get seven six-footers in the Prius+, even if the rearmost passengers won't want to be there for too long. Never the less, the practicality and intelligent management of space is thoroughly impressive, and families will find a lot to like.
The five rear seats, which fold flat and create a level load floor, have a brilliant one-hand-one-movement operation, so parents with one arm full of wailing child can still set the seats up just how they need them.
The boot lid is a little too heavy to be ideal, but it's something you work around. With all the seats up there's 232 litres of space, which isn't a great deal but can hold a reasonable amount of soft baggage. With the third row folded flat there's a much more impressive 784 litres, which is more than enough for the vast majority of families.
Under the removable boot floor there's a useful extra space for oddments. If the Prius+ majors on practicality, it does pretty well at in-town driving too.
One of the three selectable driving modes uses electric power only as much as possible, keeping urban emissions — and fuel costs — to a minimum. The battery is small compared to that of a plug-in hybrid so its range in EV mode is only a few miles at best, but it's surprising how well the Hybrid Synergy Drive makes that power last once you're rolling.
Things aren't so positive out of town. The excellent ride quality from soft, comfortable suspension means that handling falls way down its list of abilities.
Equally, the constantly variable transmission (CVT) gearbox that's gives smooth and quiet running at low speeds can allow the car to feel a little strained when accelerating up to highway pace.
But despite that, the ride is still very good and fuel economy at a motorway cruise
is very impressive for what amounts to a 1.8-litre petrol car. As always for a Prius, the seven-seater is crammed with kit.
Barely scratching the surface, the T4 model features a rearview camera — although it's not entirely reliable as a judge of positioning because it's offset to one side of the number plate and gives a slightly false perspective — a panoramic roof, automatic windscreen wipers and a touchscreen infotainment system.
The mid-grey interior trim is designed for an older audience. It's totally unpretentious and will wear without looking worn. It's practical and unassuming; perfectly suited to the Prius+ target demographic, but some will call it too bland — or worse.
The truth is that this isn't a car designed for a mass audience. It's built to satisfy a specific set of needs, and how much your own requirements overlap what Toyota's engineers were working to will reflect how good the Prius+ will be for you.
People who need a seven-seat MPV with low running costs, oodles of practical touches and unimpeachable reliability will find living with this car an absolute joy.