It would be useful to get a meter on the charging demands, so that you could find out just how much energy you are putting into the car to do your charging. After all, you pay for the electricity, and Chevy's estimate of "equivalent of $1.50 gasoline" sounds a bit low, but maybe not... I'd like to know what's going into both ports, the gasoline and the electrical ports.
One way or another the next few decades will see the end of private low-efficiency IC engines running on fossil carbon ... as the transportation of the masses. That will be unaffordable, which is how most people will increasingly experience it, rather than "unsustainable," which of course will be driving the unaffordability.
At the moment these electric vehicles and hybrids aren't economic, because they are "bleeding edge" new technology, and because the fossil fuels and pollution they produce are underpriced.
Large technology shifts are always painful, and often it is not clear what the winning technology will be. In this case it may not be batteries, there's a possibility it may not even be "automobiles" in the sense that they remain affordable to everyman. GM and the automakers investing in these battery cars are making a bet that they can improve the technology and costs enough to permit the automobile as an "everyone has one" product to continue into the future.
Certainly, it's fair to ask what the cost to operate the vehicle is. These discussions often generate more heat than light, but if you play engineer, and draw a circle around your "system", you can ask sensible questions. My first circle would cut through the gas filler, and the electrical connection. Forget for a moment all the hoo-rah about generating the power, or getting the petroleum refined... those arguments become less and less easy to verify. However: you can easily know the cost and amount of gasoline going in the tank, and the cost and amount of electricity going into the battery. The result is a cost per mile for a particular Volt in a particular service. Not much to argue about there. For those of us for whom a Volt won't work (I drive an FJ Cruiser, and for a reason) we can at least enjoy the benefit of the noble, environmentally sound sacrifices made by Volt drivers (small car, limited capacity, no towing) so that we can drive our big, heavy SUVs. ;-)
My fear is that the "one way or another" in which we may see the reduction or demise of "low-efficiency" IC engines is that the Environmental Persecution Agency continues to levy unrealistic demands on the oil industry, and increasingly screwball requirements for fleet efficiency. (50 mpg? 75 mpg? 250 mpg?). And as far as the efficiency of an IC engine goes, what is it inefficient in comparison with? If we want to compare efficiency, let's do it from well known start and end points. My suspicion is that when electrical supply chain efficiencies are taken into account that gasoline won't look so bad. At the rate people demand "sustainable" this, that, and the other thing, we won't have any freighters on the ocean that are not powered by sail...
There is a device for determining how much household electricity is used to charge the battery in an EV. It's called "Kill A Watt", from P3 International (www.p3international.com). It is not overly expensive (I paid US$25 several years ago) and plug into a household 120V/60Hz oulet (NEMA 5-15). Several versions of the Kill A Watt are now available on-line and at the major hardware and big box renovation stores. I use mine for measuring the consumption of new appliances to get a baseline. It has a set of buttons to select the display parameter (Volts, Amps, Volt-Amps, Watts, Power Factor, Frequency of the incoming AC power and Kilowatt Hours).
"Virtually sold out" because they've built 5% of the 100,000 planned, due to low demand since February's Chevrolet Volt 400 disaster ... http://placeitonluckydan.com/2011/05/nascar-pulls-plug-on-chevrolet-volt-400/
The capacity of the Volt's battery is 16 kWh, but to increase the number of charge cycles, Chevy has limted the useable capacity to 10.4 kWh. Due to charger losses, requires about 12.5 kWh to fully charge. At 12 cents per kWh (national average is slightly lower than this) the cost to charge is $1.50.
The miles per gallon rating achieved in the electric mode should also be modified (improved) to reflect that the short distance commuting miles covered in electric mode are the very miles for which the gasoline engine would have achieved the worst mpg. Doing errands around town typically achieves very poor mpg and these are the very uses for which a PHEV vehicle has the potential to work entirely with the battery.
So how is this better than the Mini Cooper SD which achieves around 60mpg using just fuel without any battery charging?
People often forget a huge hidden cost in EVs: the amortised cost of replacing the battery. Depending on various factors, you might be looking at $5-$10k per 100k miles - about the same cost as diesel.
EVs might be fine as novelty vehicles, but the reality is that in most countries the grid is already maxed out. Even a 20% market penetration by EVs can't be achieved without a huge build-out of generation and distribution. When that rolling blackout comes, you won't get a charge.