The volume of the tank on your Series 5 Gran Turismo is 12L.
Below 1500 miles of mileage, a warning is displayed on the dashboard and a alarm signal sounds to warn you to fill up your tank. Below 650 miles, an AdBlue® warning appears on the dashboard, along with an alarm sound and a message that warns you that restarting your car will be impossible once the tank is empty. If the tank is empty, you will be warned by a message and 3 audible alarms. Once the engine is turned off, it can't be started again.
If your tank is completely empty, you cannot start the engine again if you top. If your engine is still running, you are able to drive to a service station to proceed to the replenishment of your AdBlue® tank.
This information can vary on some vehicles of the same model in relation to the options chosen by the manufacturer.