Still feeling guilty for not using public transportation? Your green sins may soon wash away with Honda’s H20-emitting FCX Clarity, the latest step in hydrogen-fuel-cell technology. The new sedan will be leased to SoCal drivers starting in the summer of 2008, and will become available to the rest of California in the near future. The biggest hurdle to the fuel-cell market is the lack of fueling stations, which Honda hopes to solve by sticking “Home Energy Stations” in garages around the country. And if you’re convinced that size does matter, next year General Motors will put 100 hydrogen-cell compact SUVs on the road in test markets. But in the meantime, you really should take light rail.