It brings back memories of the Quasar, a semi shelled motorcyle from the 70's, talking about a cycle car or trike, what about the concept Suzuki GSXR4. You kind of need a Volkswagen Beetle, cheap light weight, but looking like it just stepped out of the future. 2 wheels foreward and 1 wheel behind is the most stable, reverse it and you take corners with one wheel in the air. The Sparrow was close to that cool cycle car trike concept, but high prices and a number of things kept it from really taking off.
The potential is there, Europes high cost of fuel brought the micro car revolution, I think as long as we keep scribbling on paper someone somewhere will make that perfect car. Then there's the safety thing, a car made from paper machet and balsa won't stand up against an SUV on a cell phone.