GENERAL MOTORS LEADS in fuel-cell patent rankings. Honda is #2. I drove a GM fuel-cell car a few years ago for Popular Mechanics. My impressions are here.

Plus this: “The car advertises itself as petroleum-free, which is true. But—and here’s my problem with hydrogen cars—it’s not really fossil fuel free. Most hydrogen is made by ‘steam reformation’ of natural gas, which is still a fossil fuel. You can also make it out of water, via electrolysis, but unless you’ve got a non-fossil source of electricity the hydrogen is really just functioning as an energy-storage medium, rather than a source of energy. Of course, build lots of nice, clean nuclear plants, or orbiting solar power plants, or whatever, and that problem goes away.”