Which would need an order of magnitude higher power carrying capacity. The present grid could not support such a load in its slackest times, let alone during heat waves.
You're right, the grid needs to be upgraded. That seemed pretty apparent a couple of years ago out west. However, electric power (nuclear and coal) is cheaper than oil power and much of the charging of autos could be done at night, off peak, and even smartly regulated. And the worst case is you might have to use a little gas anyway if you don't get enough of a charge.