Electric cars are usually charged from the mains grid electricity, which is predominantly powered by

Electric cars are usually charged from the mains grid electricity, which is predominantly powered by fossil fuels.. so what's the point?
First and foremost, your mains electricity no longer needs to come from fossil fuel power stations. In almost all parts of Australia, there are now "Green Power" options which ensure that the power you use is coming from renewable energy sources. Everyone should consider switching to Green Power, even if you don't have an EV!

That said, even when charged from mains power based entirely on fossil fuels, driving an electric vehicle results in far less greenhouse gas emissions. Power stations use fossil fuels much more efficiently than internal combustion engines, and electric motors themself are very efficient. A common measurement for real vehicle efficiency is "well to wheel" ñ as in the quantity of oil taken from a well required to drive the car a given distance. For a comparison, the all-electric Tesla Roadster supercar is approximately twice as efficient well-to-wheel as a Toyota Prius.

Another interesting point is that it tends to be uneconomical to down-regulate power stations during off-peak periods, such as at night. During these times, a lot of power is simply dissipated (wasted). This could instead be used to recharge a huge number of electric vehicles. For example, in California enough power is wasted every night to recharge 4 million electric vehicles!

And lastly, many people opt to install solar panels on the roof of their home or business premises to become energy and carbon neutral - then you can truly say your EV is zero emission!