I have not seen anyone else build the California Commuter, yet this guy has been selling plans for years. I think the basic plan has some merit.
I spent a bunch of time checking out some of the supermileage challenge cars and events last night. There is the
SAE Collegiate Design Series: SupermileageŽ which is based on a B&S engine (what a joke, the engines have nothing to do with what they start with), and this one;
Shell Eco-marathon Americas 2012 Open For Registration | Global. There also some run for high school kids.
These "cars" are purpose built for the challenges and incredibly fragile. At the same time they are getting into the thousands of miles per gallon. I was thinking if one were to compromise by building a more reliable and practical version, license it as a moped, and drive it like a challenge car, 250 mpg would not be out of the question.
The CC has some of the compromises I would want. It has motorcycle tires and a suspension, but way to much motor to be registered as a moped. The Visibility Pod on the CC would also meet the requirement for the headlight center to be a minimum of 24" high. One area for improvement would be building a carbon fiber body shell I though the videos from this YouTube poster were very educational
http://www.youtube.com/user/fibreglast/videos
In my state Mopeds are supposed to be less than 50cc's and slower than 30 mph. This speed limit would be perfect for using coast and burn. Ideally I would like to average around 30 mph for the kind of commute I am envisioning, so after registration it might get a little faster. Another requirement in Michigan is that the operator not be required to shift gears, so either an automatic with centrifugal clutch or some other arrangement would be in order. I'm thinking that to reduce drive line drag, the driven wheel should freewheel.
Anyway, this is as far as I have gotten on this thought exercise.
Kirk