Every EV already has this API, it’s just exposed to the “charger” not the internet.
Because all EV need to negotiate with the charger their plugged into to determine if they can charge, and how fast. It pretty easy to build a charger compatible with any EV that simply caps the cars charging rate until electricity is cheap.
Here in Europe at least, there are already several companies that make these chargers, including ones that just MitM the cable between your car and your normal charger, and allow you get better rates though aggregation with other owners.
Because all EV need to negotiate with the charger their plugged into to determine if they can charge, and how fast. It pretty easy to build a charger compatible with any EV that simply caps the cars charging rate until electricity is cheap.
Here in Europe at least, there are already several companies that make these chargers, including ones that just MitM the cable between your car and your normal charger, and allow you get better rates though aggregation with other owners.