> Cars are only a small part of the total energy pie

If 80% of US drivers switched to electric vehicles, the total annual electricity consumption would be approximately 1,013,472,000,000 kWh (or about 1.01 trillion kWh). This calculation is based on the assumptions of an average annual mileage of 13,500 miles per vehicle, an average electric consumption of 0.34 kWh per mile, and a total of approximately 276 million vehicles in the US.

As a contrast, today's total output of power in the US is 4 to 4.5 trillion kWh. So capacity needs to increase 1/4 which is not trivial.

Caveat here is we keep the same efficiency in EVs.