You still can't walk into a dealership and buy a hydrogen-powered car, but if you live in Orange County, California, Westchester County, New York, or Washington, D.C., where it's easiest to find a hydrogen filling station, you may be able to borrow one for a couple years. Starting this month, in what will be the largest real-world test of fuel-cell passenger vehicles, GM's Project Driveway program is seeking good homes for 100 fuel-cell versions of its Equinox SUV. (Honda, by contrast, has leased just two of its FCX fuel-cell cars to customers.)