[rprospero]

Ah, okay, steam powered cars I've seen before. Of course, they're not so much water powered as they are wood powered. The steam car is no more water powered than my car is axle powered.

Still, now I'm wondering about the fuel efficiency of a steam powered station wagon. How much wood would a wood-Woody burn if a wood-Woody would burn wood?

[mikeash]

Steam engines generally have terrible efficiency, at least at small scale. At large scale they do well (lots of power plants are basically steam engines), but smaller scale means higher output temperature, less equipment to capture energy, etc. Wikipedia says that an engine that exhausts the used steam to the atmosphere will be 1-10% efficient, as compared with ~25% for a normal gasoline engine and 40-50% for electrical generation engines.