phones ,,, the difference between both of them is that mobile phones gets radiations thru the Air where the chance if fuel vapors are very high...

Incase of vehicle they are tested and are 99% risk free. But still it is advise able to keep the engine off while fueling. Only risk involved is the when the ignition is trigger it passes the current to the Dynamo which could be a risky too but since it is inside the vehicle and chance of fuel vapors going there is very low.

Better to be on safe side always :)

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