In 2015 the Department of Energy expects to make a decision with automakers and energy companies about whether FCVs can be made commercially viable. If things look good, the first FCVs offered for sale could be introduced soon after.

Some automakers have already announced plans to commercialize FCVs before 2020. GM has even said it expects to have FCVs in showrooms by 2012. But some experts say it will take a critical mass of 500,000 FCVs to bring costs in line. That could take until 2025 or 2030.

For flexibility, FCVs will be able to be powered by either a hydrogen fuel cell or a battery pack that, in some, can be charged by plugging into electrical outlets, says Scott Samuelsen, professor of mechanical, aerospace, and environmental engineering at the University of California, Irvine.

The next few years will determine whether FCVs are headed for the open highway or a dead end. In the meantime, weaning America off fossil fuels will take more than FCVs. Consumers Union, the nonprofit publisher of Consumer Reports, thinks the U.S. needs to pursue higher fuel-economy standards for gasoline vehicles, as well as alternative vehicles powered by clean diesel, biofuels, and batteries. It will take a variety of efforts to lead the country out of the petroleum era and into the next energy age.