Killing the environment
Electricity is not a power source - only a means of transporting it. Losses mean 4 times as much energy has to be used as reaches the socket so it is highly environmentally unfriendly, especially as most of our electricity is from fossil fuels.
80% of the environmental damage done in a car's life is in making it, not using it. Batteries don't last as long as cars currently do (16 years av) and paying £3k for new ones in a car which by then is worth under £1k is economic nonsense so cars will be scrapped earlier, increasing the environmental damage.
Batteries are extremely nasty to the environment with the heavy metals being horrendously damaging to extract and they are not recyclable. They also put us in the hands of unstable regimes with 90% of the world's lithium coming from Bolivia, for example. The additional weight and the acids in wet batteries makes them dangerous in accidents too.
Oh Gordon - why don't you read the research?