How does the electric car's range compare to similar conventionally fuelled cars, and what is the cost-per-mile for electric vs. petrol?

The range of an electric car can be significantly different from that of a petrol fuelled vehicle, as electric cars typically have a shorter range than their petrol counterparts. However, the cost-per-mile of electric driving can be significantly lower, as electricity has historically been cheaper than petrol. But of course, this is dependent on current petrol and electricity prices.