is 10% increase on EPA cycle realistic?

Or one of these:

 

I hope that means engineer?

Decision was made

Power split device and electrical/mechanical power | PriusChat

 

assume it is the same? to first order or zeroth order?

 

The explanation was that the system is more efficient therefore less peak power is needed to keep the same performance. The hints point to less conversion loss (ICE->MG1->Inverter->MG2) through the electrical path.

The fundamental idea of HSD is to use the electric propulsion when gas propulsion is not efficient. So, despite the conversion loss, the electric path has to be more efficient at the wheels, to justify the usage. HSD was designed to have optimal power of both propulsion systems to achieve one common goal (use the least gasoline).

The balance in Gen4 has changed. ICE is more efficient and EGR was improved. This means, ICE can maintain optimal efficiency at record low load (sub 15hp). A bit of history, to better understand.... Gen2 had 1.5L ICE that goes as low as 15hp without pumping loss, thanks to Atkinson cycle. With Gen3 1.8L ICE, Toyota started to recycle the exhaust gas (on top of Atkinson cycle) in order to maintain efficient 15 hp (great for highway cruise speed).

If Gen4 ICE can handle lower loads efficiently, the electric propulsion system can be downsized for optimal results. This does a few things. The mechanical path is more efficient since there is no conversion loss. The weight of battery, motor, generator, inverter, etc can be lighter and smaller -- hence cost less, further boosting the overall efficiency.

To answer your question, if the same power makes it to the wheels, it doesn't matter what the max power the system can produce. The end result is the same where it counts (at the wheels).

Well, that's my understanding based on hints and "educated" guesses. You are right, we'll have to wait and see more details.

 

They have locked the hood at the reveals, probably so we will not be able see the smaller inverter?

 

There is a hint. The 12v lead acid battery is now under the hood. That extra space came from smaller HSD transaxle, as Ken posted. That alone can't make up for all the space needed for the 12v.

 

probably cause there's nothing in there, and they're still trying to figure it out.