If you are on 15 min based pricing and charging when at home is 5 - 20x more expensive vs at nought or during the day, I think it’s a matter of time before someone releases a software update for your charger or car that coordinates charging your car with optimal energy prices.

In NL you can already get prices by the 15 minutes and sometimes I get paid to use electricity on windy and sunny days. eg see easyenergy.com. You get the prices 24h in advance, so you can even plan optimally without the need for advanced predictions.