Zero-emission vehicles (other than bicycles) do not exist -- the electricity made to power these vehicles isn't produced by fairies and rainbows.  We're simply shifting the production of CO2 emissions to an alternative source.

60.1% -- Hydro
15.8% -- Nuclear
10.3% -- Natural Gas
10.0% -- Coal
1.8% -- Wind
1.2% -- Fuel Oil
0.8% -- Biofuels and Waste
0.4% -- Wood
0.1% -- Solar

Hydro isn't as clean as you would expect -- dams can produce more CO2/Methane than some fuel-burning plants.