Filling that every 2nd day (for a measly 75 mile range) would add 50% to a households energy requirement
And households are 30% of the electric load.
So, if every household in the USA immediately bought an electric car, grid demand would go up 15%.
Which could be handled _now_ simply by charging at night. In order for the sky to fall, one must assume electric cars are incapable of using smartgrid software.