I just want to point out what I believe is almost certainly a misunderstanding of how the electrical system in this car likely will work. Many comments here revolve around the idea that the ICE generator doesn’t make the car go, that only the battery makes the car go. I’d like to remind the readers that the generator turns on when the battery reaches approx 50% charge, further that the generator, battery, and electric motor are almost certainly all on the same electrical bus (see http://www.gm-volt.com/2007/08/24/new-fact-chevy-volt-generator-starts-when-battery-power-hits-50-stops-again-at-80/).
When the battery is being charged, it is a load on the bus, not a source. What, then, is the power source that is delivering current to the electric motor – why, it’s the generator of course. The generator is powering the motor, even if via AC/DC and DC/AC converters plus harmonic function generators. The generator must make enough power to move the vehicle, and excess power can be used to charge the battery.
Now, of course, I could be wrong about this. The battery pack could be designed in a complex fashion where separate cells are ganged together and act as separate batteries, so that some are charging while some are running the car. However, this would require significant unnecessary complexity (additional high current switches, caps, etc.) Why would one bother with such added complexity? I suppose there may be other ways to create a system where one can say that the motors are truly supplied power only by the battery and not the generator. I’d encourage you to describe it. I wonder if we can post notional schematics, Lyle? Maybe you could show them to Denise Gray and she can settle the matter.
At any rate, GM does appear, unfortunately, to have to position itself to call the Volt anything that doesn’t use the word “hybrid” for much the reasons that #2 John1701a stated. Frankly, the public would never understand the distinction between what they now perceive as a “hybrid” (ie the parallel hybrid epitomized by the Prius) and a serial hybrid. Thus, a new name was born. Would not a rose by any name, smell as sweet? Volt under “EREV” still smells sweet!

All the other OEM PHEVs are not able to do this. The engine comes on for full power, or above 40 or 50 mph. So the E-REV designates it as EV all the time until the battery runs out (the volt is supposed to go 40 miles), then it becomes a hybrid.

So I get he idea the idea that an E-REV can actually delivery a particular range on eletric power alone without having to limp along. Being a just a PHEV means the engine is cutting in and out, even with usable battery energy.

It has nothing to do with series or parallel, near as I can tell.