Looks like a fun project, that wood-gas car. I wonder though if just making an old steamer wouldn't be a little more versatile (any heat source).
Since I can and do store some fuel here (buried drum) - my fallback for most things might be
my 200 mpg go-kart which is surprisingly useful around here. Tiresome on long trips, but fun to drive indeed. You just can't use up too much gasoline in that thing, and the basic platform is real amenable to other powertrains if they can be bolted on the back instead of the IC engine - I've thought about making an electric version. DoChen might want to look into importing those intro Peru or some other place where the regs on cars aren't so stiff. I did get a dispensation to drive it on roads here, but it was hard to do, and I'm not allowed to sell them as cars here.
Remember, if you have a solar farm, you've got energy. If you're not in the trucking business, range of 40 or so miles might be fine. I can do my full errand loop - to Blacksburg, Christiansburg, then back to Floyd with a lot of stops in my Volt, all electric. 3 decent sized towns in range on one trip - good enough, I hope. Right now, as I learn to drive that thing the way it likes, my range is actually going up every trip.
I'm interested in the steam thing for other reasons - these days you should be able to make a couple of pretty decent and cheap designs and again - any heat runs it, including solar-dynamic as NASA has done some work on for big solar installations.
I've been dreaming of a 3 cylinder, double action, 120 degree steam engine made from air-hydraulic cylinders - where the old boys had horsehide for piston rings, we have teflon and stainless steel, and those things are meant to run wet. Self starting and runnable over a very wide pressure envelope from whatever source of steam (And whatever working fluid, doesn't have to be water). Or about a 3 stage turbine, which gets you most of what there is from the input energy, and that could run over a truly wide range of supply volumes and pressures via multiple first stage input jets switched by pressure relief valves. Kind of take a page from those hobby steam railroader guys who make this sort of thing from scratch - and they're safe now that we know how to handle steam systems safely. I've got some good old books from back in the day that show how, and now we have better stuff to make it from.
I've been looking into that sort of thing as a possible product for 3rd world power generation...the idea is to make it real cheap, and as stupid-proof as possible. For that customer set, you make it so you can fix it with whatever is at hand - maybe the turbine blades are cast from melted beer cans - they don't last real long but in this instance, labor to repair is cheap.
That sort of thing. Keep the initial cost as low as possible. And be sure to make it safe even if some idiot overfires the boiler - that's where the turbine is good with the switchable jets.
We can thank Babcock and Wilcox for some real nice vanity books they've printed that show all the details of "Steam, it's generation and uses" - from coal to nuclear input. Before them, steam was very dangerous - killed a lot of people with explosions. Now, not so much. Those books have more arcane and real life useful knowledge than most would think could exist about water in various phases and how to handle it all, as well as how to burn things efficiently and get all the heat into something that can live a long time under the conditions. I should maybe start a thread on "books people should have if they have to rebuild a world" - because I'm a book lover, and by golly, I've got them!