Everything "smart" is running a program. You could replace that program with your own or fake environment for that program. It is not a real problem.

The problem is that you need ~80kWh to charge your average electric car. Simplifying, it could be a 80kW pushed to a car in a hour, or, 1kW pushed to a car in a 80 hours. For average household you hardly could obtain more than 5kW from a socket, so it will be minimum 16 hours to charge your car. In reality there is losses, so it will be longer.

Everything "smart" is running a program. You could replace that program with your own or fake environment for that program. It is not a real problem.