Before filling the fuel tank, it is important to **stop the engine, disconnect electrical systems, and turn off mobile phones**. This is because:

- **Stopping the engine** is essential to avoid any risk of fire or explosion, as the running engine can generate sparks or heat that could ignite fuel vapors.

- **Disconnecting electrical systems** is crucial because any electrical spark, even the smallest, can be dangerous in the presence of fuel vapors. The vehicle's electrical systems, if active, can generate these sparks.

- **Turning off mobile phones** is an additional precautionary measure. Although the risk is low, mobile phones can, on rare occasions, generate sparks that could ignite fuel vapors.

These measures are part of **preventive and efficient driving**, ensuring not only safety during refueling but also the proper functioning of the vehicle.