My personal opinion is GM is better served with the minivan approach. Too many plug-in cars in the market today are simply too small, too low. Why not offer something different, creating a new segment of the market where there is less competition?
The market consensus right now is the Volt 2.0 will be the more simple and straightforward approach of the current low-slung body with a T-shaped battery, albeit making way for a fifth seat. I think the probability of the mini-minivan approach is a lot closer to 50% than the market's current near-0% probability.
The basic Volt 1.0 performance concept is unlikely to change, and for good reason: GM got it exactly right the first time. The Volt delivers the first 38 miles on full electric power. I emphasize the word "full" here because in other plug-in hybrids, electric drive isn't delivered for the full performance envelope of the car.
This makes a huge difference. There is a world of difference between being able to floor the accelerator 100% until the car hits its 100 miles per hour top speed and the gasoline engine not kicking in -- as opposed to it kicking in. There is just no comparison. One car -- the Volt -- is fun to drive; the other plug-in hybrids are not. The one exception is the BMW i3 with range-extender.
If GM doesn't get this, it will lose its buyer loyalty and the second-hand value of the Volt 1.0 may actually increase. I think GM gets it. Let's see.
GM will obviously try to improve the Volt's efficiencies all around. Depending on the size and weight of the new Volt 2.0, electric range may or may not be longer than the current 38 miles. The efficiency after the electric miles run out, when the car goes on gasoline, will likely improve from the current 38 MPG to perhaps 44 MPG.
The interior of the Volt 2.0 is likely going to see three major improvements from the 1.0:
1. Better center stack controls. Let's bring back conventional buttons and knobs, please? Something that is neither confusing nor difficult to operate with thick gloves in the winter. The Volt team should consult its sibling development team in charge of the full-size Silverado pickup.