The battery-powered cars are much more energy intensive to build than gas or hybrid cars, based mostly on the cost of producing the batteries themselves. For the use phase of the analysis, they also did three different examples for the electric car, based on the energy source for the electricity. When using electricity from coal, the total CO2 emissions for the electric car was almost as much as the gasoline car and almost twice as much as the hybrid. Electricity from natural gas was much better but still not as as good as the hybrid and the cleanest by far was the EV with hydro-electric power.
However, one thing that seems to be missing from this analysis is the post life phase. How much energy is used (and subsequent CO2 emissions) will also vary for these different types of vehicles. The iron and aluminum that comprise most of the content of an internal combustion engine are fairly easy to recycle by simply melting down and re-casting. Disposing of batteries is substantially more complicated.
[Source: Institute for Lifecycle Environmental Assessment via TreeHugger]