Yes, you sure do.
To reduce the risks of a fire.
Because there is a risk of fuel ignition due to static electricity buildup and discharge. Gasoline/petrol is extremely volatile stuff.
not enough octane in your petrol. To stop the run on, turn your engine off while it is in Drive. Then switch to Park
A petcock is a fuel swich on the petrol tank that can turn the flow of petrol to the engine on and off. It usually has a on, off and sometimes reserve setting.
because it is out of petrol and broken
Improper Engine Tuning in Petrol Engine.
Leave Engine Off
Sounds like your float is stuck in the carburetor.
Does it stay there permanantly? If so check you've filled up with the right fluid; • Petrol • Deisel
because if the fire off the cigarette touches the petrol then the whole gas station could blow up
It is necessary because if the engine is still on, it will use up the petrol you are filling up.
Yes, to avoid a spark from the car's electrics igniting petrol fumes (gas), it is mandatory to switch off the engine while refuelling. There should be a notice at the pumps telling you to switch off the engine.
you cut off the ignition spark in a petrol engine