Hello Ben,
This is my first post on EcoModder.
If you want to learn more about wind turbines, there is one website that I think is far and away the best website on the subject.
Welcome to OTHERPOWER.COM
I recommend you begin on the following page:
Wind Power
That page has a list of a wide variety of different experimental home brew projects. Some are obviously inappropriate for your use.
The website is especially good if you are interested in BUILDING YOUR OWN using scrap parts. The site has been built by a small group of home owners in the Mountains that live many miles away from the nearest powerlines.
I also suggest checking out the Godfather of Homebrew Wind Turbines, Hugh Piggot.
Hugh Piggott - Scoraig Wind Electric
His axial flux generator design is the best one out there, IMO.
Now that I've given you those places to look, I'd like to offer my editorial opinion on your demonstration idea.
Please think through the message that you are sending. BE CAREFUL.
Think about what message you are wanting to convey to your audience. How many people will walk by your car with a tiny wind turbine and not ask questions? How many won't bother to read whatever signs or papers you are handing out? Just having a tiny wind turbing sitting next to an electric car could be misleading to many people. The uninformed casually walking past may get the impression that a small turbine is practical to power a car. I realize YOU know better, but will the average pedestrian understand as they walk past your display?
Also, there is a great deal more to wind power than simply having a turbine. In fact, the wind turbine itself usually only represents 1/4 to 1/3 of the total cost of a wind power installation. The site location, wind conditions, charge controller, low loss electrical cable, and most importantly, THE TOWER add more cost to the project than most people realize. (Roof mounted Wind Turbines are a MASSIVE MISTAKE in almost every circumstance.)
In my humble opinion, you'd educate an average person far more effectively by having a poster with a picture of a LARGE wind turbine on a big tower sitting next to your car. People wouldn't get the wrong impression that way.
Please don't misunderstand. I'm an advocate of Wind Power. It's just that there are a lot of snake oil salesmen selling small turbines that really don't do much. I'm confident that you are honest, but I'd hate for you to accidentally misrepresent the real capabilities and send someone down the wrong path.
I hope you find the links fun reading and helpful.