lyeinyoureye

In my head, I'm almost finished!
Spec wise it's pretty easy to map out since it's all been done before. Let's use a vehicle that's as aerodynamic as the best hpvs we've seen, but ~2.5 times as wide, no need to feel like a sardine. Roughly speaking, the energy we loose to fluid friction at ~25m/s~55mph will be the largest source of "lost" energy, so if we drive around town, we'll use substantially less. At 55mph this glider with CdA=.092m^2, Crr=.009, W=500N (aka kg) will need ~(500).009N+.6(25^2).092N=4.5N+34.5N=39N to overcome fluid and rolling friction on flat ground with no wind. It will need 39N(25m/s)=975w, or 975wh over an hour, or, at 55mph, 975/55=~17wh/mile.

Let's go EV geared appropriately with drivetrain efficiency at ~75%, so we need ~23wh/mile. If we're not obssessed about performance we can go with Saft STM NiCD batteries in an insulated box with a high R value. Lets say we go with a 6.7" advanced motor (or we can go cheaper), .75-9hp with appropriate single speed gearing. We will have 36v(100ah)=3.6kwh available, and since we use about 1.3kwh to go 55 miles, this pack should give us a shade under 150 miles all electric. More than what's needed for the average commute. Assuming we're the average driver, and driving 10,000 miles per year, we'll need ~230,000wh per year, or ~230kwh per year. According to the Purdue University Horticulture dept, one ha of Jatropha Curcas can provide ~20,000kwh per year. Since a ha is ~2.5 acre, we'll get ~8,000kwh per acre. Now converting this fuel to electricity will incur a penalty, lets say we have a diesel genset/ battery charger with ~25% efficiency, so that 8,000kwh is only ~2,000kwh once converted to electricity. Let's say we only have 1/5th of an acre to work with, and we suck at growing stuff, then we'll only have ~400kwh with o.k. yields, or ~200kwh with crappy yields. Alternatively, a 100-200watt solar panel may provide ~1kwh per day, more than enough for the average commute. Of course lights, a radio, whatever electrical crap you want to add will decrease range, but it depends on what you want.

Now, this little beast will require ~80kg in batteries, maybe ~50kgin the drivetrain, 200kg for the rolling shell, and ~80kg for the driver. So ~400kg. Add another 100kg for good measure, and we're at our target weight. The frame should be a unibody exoskeleton (ala the arieal atom) that will provide a protective cage for the driver, or cager if you will. They should use a racing harness and motocycle helmet for added protection, as well as significant padding on the frame where the driver may hit it in an accident. I think the body should be made from paper mache due to cost, ease of repair, and coolness, but we can do fiberglass or carbon fiber if we have the cash. Acceleration will be a bit lacking, kinda like a 80s economy car, but energy efficiency is the goal. A 1kw gasoline genset can be adding if we want the range liquid fuels provide.

An excellent demonstration of fluid friction is to take two pieces of paper. Ball one up into something the size of your fist, and the other as much as you can. Then throw each one as hard as you can at a 45 degree angle and observe which one goes farther. If something has more volume, it takes more energy to move through a fluid. This is why semis are long and rectangular, instead of boxy like SUVs. Vehicles with ICE engines are built to be inefficient, but they don't have to be.