Here's how I see it...
Any time you change states of energy (fuel to HP, HP to electricity, electricity to HP, etc) you lose a significant amount. I don't understand the value (other than placating an uneducated mass of consumers) of these vehicles.
The bottom line is, if you need to get X hp to the ground the most efficient way of doing it is with the least amount of changes of energy; fewer direction changes like in a rear axle, less friction, fewer energy conversions.
The Volt goes like this:
- uses energy in fuel, converts it to kinetic energy (hp) with an engine. That step alone can only hope to be about 30% efficient. The rest of the energy is wasted as sound, heat, friction, and light.
- uses the engine's hp to drive a generator and make a different kind of kinetic energy; electricity. That process can only be about 80% efficient. The rest is lost as heat and friction.
- uses the electric energy to turn motors, again about 80% efficient.
So, its releasing stored energy in fuel to convert to kinetic energy, then to electricity, then back to kinetic energy. How can that possibly be more efficient? That's like plugging an inverter into your 12v outlet so you can plug in a 110v phone charger which converts back to 12v anyway. Or its like putting a windmill on an electric car; you will spend more energy pushing the windmill through the air than you will get in return from the spinning windmill.
As an amateur engineer, I think the smartest way is the least complicated. Either find ways to generate or store greater electrical capacity so the engine isn't needed, or just put a diesel in it 
