<http://carpoint.msn.com/as/autoshow2002/ArticlesGM2.aspx

The trouble is the General Motors Autonomy is an exotic car running on an exotic fuel. The design conditions required to allow large-scale use of hydrogen fuel would also allow large-scale use of ethanol and biodiesel with internal combustion engines, which could easily be less expensive than hydrogen fuel cells. The necessary conditions are extreme fuel economy, around 200 mpg, which is 4-times better than any hybrid-electric car on the road today. To achieve it cars need to be "cargo-proportional" in size, for example this one-seat commuter trike made by Windcheetah in UK. It does indeed carry one person, without the weight & bulk of an SUV:

Or this fully enclosed one-seat commuter trike made by Greenspeed in Australia:

Two-seat chassis are available from Greenspeed too:

They are quite expensive however due to limited production. If you want to build your own, IE Systems sells chassis kits starting at $200, and all you need is a stick welder, and a local bike shop to buy your own custom wheels, gear sets, etc. And if you are really ambitious, or plan on achieving higher speeds, you might want to retrofit some suspension components such as McPherson struts, shock absorbers and springs...

After building your own chassis it would be a minor job to retrofit such a vehicle with an engine, such as the Briggs & Stratton Intek Model 20 which is used in Mini Baja and Supermileage competitions:

But it runs on gasoline so if there is a fuel shortage you'll not have achieved anything. American Carburetion sells conversion kits for the above engine (and many other engines) to allow it to run on gasoline, propane, or natural gas (which means it can burn hydrogen as well). But these are all fossil fuels and hydrogen may still be too expensive. The cheaper renewable fuel alternative may be ethanol. What follows are:

1. How to modify your engine to run on alcohol fuel

2. How to make your own home ethanol refueling system. One might consider an electric rather than woodburning version IMO, better for air quality in the city.

3. How to grow Jerusalem Artichokes as a high yielding ethanol feedstock

You dont' have to listen to a word I say, but if I had enough money I'd be doing all this right now. In fact it may be a good idea for a small business startup, once one has hands-on experience!

This is fun. I love html :-)