The phrase "whole lot bigger" is more aptly applied to the Prius family growing by 200 percent to three variants, because based on the profile shown on the billboard, there won't be much more to the Prius MPV than there is to the Prius hatch. Which is likely the point – a Sequoia-sized Prius just wouldn't be a Prius. We've been told before that the prototype was about the size of a Mazda5, and inside that slightly larger form will be three rows of seating made for seven human backsides. Underneath we suspect Toyota engineers will use some of that extra room for more batteries to assist a version of the hatchback's four-cylinder engine.
The other vehicle that's rumored to make up this expanded Prius model line is a smaller, compact-sized car that we expect would steal the crown for King of MPG in this land from the original Prius. Prius Chat says that the larger Prius will be called the Prius V (called the Prius Alpha in concept form) while the smaller one will get the Prius C designation. Thanks to Danny C. for the tip!
[Source: Prius Facebook, Prius Chat]