We've seen plenty of promises about water-powered cars (among other things ), but it looks like Japan's Genepax has now made some real progress on that front, with it recently taking the wraps off its Water Energy System fuel cell prototype. The key to that system, it seems, is its membrane electrode assembly (or MEA), which contains a material that's capable of breaking down water into hydrogen and oxygen through a chemical reaction. Not surprisingly, the company isn't getting much more specific than that, with it only saying that it's adopted a "well-known process to produce hydrogen from water to the MEA." Currently, that system costs on the order of ¥2,000,000 (or about $18,700 -- not including the car), but company says that if it can get it into mass production that could be cut to ¥500,000 or less (or just under $5,000). Head on past the break for a video of car in action courtesy of Reuters.[Thanks to everyone who sent this in]