It is always risky to try and analyze a car from the images but one technique is to scale and combine images to see if we can gain insights otherwise missing. In this approach, I use the tire size and sideboard height as the 'known' units to scale the images between the Prius c and existing 2010 Prius, ZVW30:
This image suggests the "Prius c" is moving towards the Honda Civic or even CRX sized vehicle. It might make more sense to go two-door with a weight savings and improved access. The rear seats being more for small children, dogs, or mostly folded down to make more cargo space.
This shows the "Prius v" and ZVW30:
Now to compare the "Prius v" and "Prius c":
I see the "Prius c" as competition for the compact cars: Jetta, Minicooper and Civic. If the scales are right, it may come in at ~2,500 pounds and I would expect and advanced technology, 1.3-1.4 L engine . . . if Toyota has one in the works. I would also expect to see the inverter and A/C compressor being located outside of the engine compartment . . . say under the driver and passenger seats.
Of course this is all harmless fun and speculation. Folks with more time might make a tracing of each body style and achieve a better view. The size of the "Prius c" driver door does seem too small to support North American bodies.
Bob Wilson