* If you mean the car charger is unplugged from the car's power outlet, then it is definitely off and not working. It's not getting any power, so it can't charge anything.
* If you mean the car charger is plugged into the car's power outlet but the device is not connected, then the car charger is on in the sense that it's receiving power. However, it's not working in the sense that it's not charging anything.
* If you mean the car charger has a switch and you have turned the switch off, then the charger is off and not working.
In general, a car charger only works when it is plugged into a power source AND a device is connected to it.
Let me know if you had a specific scenario in mind!
