A normal automatic works with a torque converter, and it pushes the car.
No such mechanism exists on Prius.
Free running gears pushes nothing. That's the Prius neutral gear position.

Ken@Japan

OK I understand how neutral works and we are just playing with words now really. With the sun providing no resistance to movement the motion from the ICE takes a path of least resistance and does little to move the car. Neutral is really just a side issue that came from my statement about "whenever the ICE is running". Perhaps I should edit in the extra words "....and in gear". Sorry my imprecise language skills have got us OT.

One final note...
Please understand that there are no mechanical differences between N, D and B position.
Only the P position moves a pawl to lock the drive gears.

Ken@Japan

Ok thanks, I really do understand HSD pretty good. If I understand correctly you can include "R" as well. Basically the entire mechanical driveline does not change, reguardless of position of the shift selector. The changes are all electric.

I'm probably going to muck this up, but it is really compu-electro-mechanical. The mode selector is nothing more than a communication system to the ECUs. The ECUs then make desisions and hand out directives to the MGs and ICE as to what they are supposed to be doing.

Toyota could have chosen to use the current joystick, or use an entirely pushbutton system or even a collumn shift you would see out of a pickup. Prius I's selector was a lever but beyond the park position which actually physically activated the parking pawl, the other points on that lever, R N D and B were still electonic selections. Instead now they have a joystick for making mode selection and a pushbutton for park, which is now an electro mechanical operation. Reminds a bit of an Edsel and its pushbutton tranny.

Placing the selector in different modes prompts the computer system to operate the MGs and ICE in different manners. The gearing is basically fully engaged at all times and there is full contact between all the components in the drive system at all times. That is partly the reason why any lenghy towing in neutral is frowned upon because forces from front wheel road movement turn items in the PSD complex and there is potential for unintended voltage generation and overspinning of certain components. Unlike a conventional automatic that when placed in neutral does disengage from the engine, that doesn't happen in the Prius neutral.

I hope I'm not being captain obvious here.

It has been said:
Hybrid drivers come in 3 flavors, greenie, techie and cheapie. Pick any 2.
2005 Prius, Melinium Silver over gray, package 5 (AI)