For the past year, we've had a PG&E time of use plan, which is cheaper after 9pm, when we charge our car.
According to PG&E's online tool, we save about $20/year on our bill compared with the regular tariff. But we could save an additional $35/year if we were to switch to the plan that's specifically for EV owners.
I haven't verified these numbers myself, but I was surprised they're so low. Perhaps it's because we don't drive a lot.