Hybrid electric cars are a pretty good idea but are most likely an interim solution. Fuel cells, be they straight hydrogen oxygen powered or ones capable of using other fuels (alcohols, natural gas, gasoline, etc.) are still too costly for near term mass production. The cost per kilowatt is coming down for fuel cells, but it's still too high today.

Pure hydrogen/oxygen fuel cells would be cheaper than the other types because they wouldn't need a catalyst to split the hydrogen from the fuel. However, there are much larger issues like the lack of infrastructure to produce and distribute massive quantities of hydrogen and storage problems, both in the vehicles and at the distribution points.

In the near term, hybrid electric vehicles make some sense but they also are hampered by weight, complexity, and expense issues. In the intermediate term, say 10-20 years from now, look for multifuel fuel cells to become viable. In the long term, pure hydrogen fuel cells will probably win out. It'll take a long time and a lot of money to develop the necessary infrastrure, but I believe it'll happen, probably in the 25-50 year range.