A little expensive, but any concept starts out that way. Also swap out the carbon body for something a little more practical and you've got a nice in-town car. Like the natural gas car, the 200 mile range will make trips difficult but imagine if everyone in a large city were to switch over to one of these for their daily commute. Not only for the fuel savings, but also environmentally friendly too. (assuming you can find an alternative to coal to make the electricity)
I just can't see how natural gas is the solution when every winter the price goes up. We're just switching from one fossil fuel to another.