No its smaller than the prius liftback, but still big enough for the market. Toyota Launches Aqua Hybrid in Japan | Hybrid Cars
party pooper . Different calculations in Japan and USA, up to the cover vs up to the roof. It is about 10% more than in new Yaris, so usable, especially since it is hatchback.
That should be still O'K since US ratings for GenIII are 23cu.ft. For comparison Mazda3 hatch is also 17cu.ft per EPA rating