Yes, I read it.  It's like the Honda in that regard.  But the Prius is not seriously different.  The design of the mechanism is different, and it can run on electric alone - but not far enough to matter.  All of the designs use gasoline as their primary fuel source - the design goal was a very efficient gasoline powered car, and the entire design is optimized for that.  A vehicle that was designed to be a plug in hybrid would end up rather different in design.  At a minimum, the battery, charging, and electric motor portion would need to be beefed up.  If the performance of the gas engine were retained, that would mean that it would simply be more expensive and heavier, as you would only be adding to what is there.

A plug in hybrid might work better as a series hybrid.  It would be essentially an electric vehicle with an on-board generator with sufficient capacity to allow it to cruise indefinitely on gasoline - perhaps with reduced performance, but it does not take all that much power to cruise on the highway at a reasonable speed.  It will take quite a bit of development time to produce one.

Whatever happened to flywheel storage?  I always thought that sounded like a really good solution.