All electric cars are NOT zero emissions. You have to examine the entire "stream" of energy. The energy produced to charge the batteries has some sort of emissions related to it.
If you live in an area of the country where coal is the primary source of your electrical power, and the coal fired generation is old and dirty, why bother driving an electric car?
Right now, the interesting technology is self contained units like fuel cells or hybrids. Hybrids offer real efficiency gains, right now. The problem where I live is the cold. Hybrids don't like it, especially systems like Toyota's where the electric motor provides drive force. In cold weather, the gasoline engine must run all the time to ensure that the occupants have heat.
The Honda system uses the electric motor as an assist, not as primary drive force, and suffers less in the cold.
Also, all current battery technology has cold limitations. Cold weather reduces their life, their efficiency, and this in turn reduces the advantage of hybrid/electric technology in certain climates.
In fact, if you look at highly efficienct gasoline only cars like the Civic or Echo, they are very close to hybrids. The price difference makes the hybrids unattractive. The real key to reducing fuel consumption RIGHT NOW is legislating lower sulfer levels in diesel fuel, and importing superb European turbo diesel cars/trucks. VW sells a car capable of attaining 3L/100 km's (80US mpg) in city driving, and I undertsand it's a much better driving experience than the hybrids. Of course, there are emission problems with diesels, but they are so much cleaner than even gasoline cars of just a few years ago.
An ML270CDI gets the same mileage as a family sedan even though it weighs as much as an S-Class and a motorcycle together.
1998 C230 "Black Betty"