Utilities have existing techniques for distributing that load. They already work with smelters and other large power users to coordinate their power demands. I

Utilities have existing techniques for distributing that load. They already work with smelters and other large power users to coordinate their power demands. In some places utilities are offering discounted electricity prices if the car charging infrastructure is hooked up to their smart metering/control system. This allows the company to signal when cars should start/stop charging. There's no reason they can't work with car makers to introduce two way signalling between the charging infrastructure and the grid - the car can tell the grid that it needs to use X kW by Y time, and the grid can communicate the current permitted load. Potentially with some option for the customer to pay a premium to charge immediately at a higher rate.