Re: I dont get it.
Why would you create *more* pollution?
At the very worst you would expect to create the same pollution but not directly in the streets and residential areas. However a power station is much more efficient so there will be less pollution.
The real benefit comes with the upgrade though. Try to get 1/5th of cars to be more environmentally friendly using a new power source (new cars, closing of existing fuel station, new delivery network) and you are talking decades with major opposition.
If a large amount of people are using electric cars with it's national power grid sent all over the country already (you can even build you own fuel station directly in your back garden) and any upgrade to a power station immediately upgrades every car to a less polluting power source.
Build another few nuclear power stations and the day it is switched on and a coal fired one is turned off then you immediately have a massively less polluting (without getting into waste issues) power source. Crack the fusion power station problem or get in reliability in the delivery of renewables and every car also benefits (along with every house, factory etc).
Electric cars give the option for changing the power source after the fact and getting them into peoples hands before building the new fuel stations.