Perhaps people should just try to imagine a big barrel of water. there is a spicket at the bottom that feeds the motor. At the top are a few smaller hoses filling up the barrel. One is from the garage plug, one from the brake regeneration, one is from the ICE generator and one is from the solar panels on the roof (sorry, I just had to).
If you conceptualize this simple model almost all answers can be visualized very easily. For example. How fast can the car go on a flat road for an extended amount of time if the governors were disabled (yeah, some hacker will figure this out). Answer? Just think of the barrel. The bottom spicket is open up full and it’s a BIG spicket. What is feeding the barrel? Garage plug? Nope. Regen? Nope. Solar? Of course because it’s a beautiful day in Texas - for this example however assume it’s nighttime. ICE generator? Yep! It’s the only hose filling the barrel. Unfortunately, it’s only 55 kW - much smaller than the size of the spicket feeding the motors. Thus, when you have the pedal to the medal the motors will attempt to suck as much from the bottom spicket as possible. Thus the barrel will start to empty, even when the ICE is running flat out. When the barrel empties to the place they stick the spicket in (say 30% from the bottom) no matter how hard you press the pedal it will NEVER be able to produce more than what is being dumped in - 55 kW. Thus, you can calculate the long term running speed with little difficulty. Easy huh?
Let's take another one: I want to be able pass cars when I want and have a much more lively feel than the tiny ICE alone can give me. How should I set the ICE start and stop points to achieve this? Simple! First you ask how much power do you require and for how long. Next you have to ask at what interval this maneuver will be needed. For example. To pass a truck I may need 70 kW for 1 minute. I figure I will not have to do that again for another 5 minutes. Ok, now that you have your barrel model you can easily calculate the set points and ICE generator loads. You will only have the gen-set pouring into the barrel in this example (you are on the highway again and not using your brakes) so it is easy to calculate. You will need an additional 15 kW for that one minute so all you have to do is determine what point above the spicket the water level needs to be. Maybe that comes out to 40%. Done. Thus, you better make sure the barrel is at 40% before the truck passing maneuver is attempted or you will drop down to 55 kW too soon. Since you have 5 minutes in-between maneuvers and normal highway driving only requires a small fraction of the ICE's generator capacity you can actually determine the minimum amount of power the generator needs to produce for that 5 minutes. Cool huh?
From these simple examples you can begin to see how difficult it will be to determine these settings for different styles of driving and for different drivers and loads (like the poster above mentioned - 4 people driving up a hill - with that example you can easily calculate the maximum speed the Volt will be able to climb that hill - it will soon only be able to give you 55 kW after the spicket level is reached).
I'm thinking that version 1.0 software will have different set points and gen-set loading for different conditions (highway, city, hilly terrain, heavy loads, light loads, etc.) Next generation software will have AI that can learn your driving style and run the gen-set accordingly. For me the gen-set could be run mildly. For a high school hell raiser you might have to keep the ICE running flat out at all times until 90% charge is reached and then start up again when the charge drops to 80%. That way the barrel will be able to supply maximum power to the motors as frequently as possible. I hope they put parental controls on this thing!
This is why I never understood why people kept arguing that the ICE will directly run the motors and follow the load of the pedal exactly. You can see from the barrel model that by doing that you will not be able to re-fill the barrel in time for the next extreme maneuver. While the ICE engine may be made to seemingly follow the pedal movement so the driver is more comfortable in reality it would be more efficient to get the barrel to the proper level within the predetermined time frame. If that time frame allows varying the ICE with the pedal movement for a more natural sound then fine, whatever the customer wants. However, I don’t care about that. I want the ICE to run as efficiently as possible to get the barrel to the level the software has determined is best for my driving style and situation. Of course, I would like the ability to set it to hell-raiser once in a while.