Methods and systems are provided for aging a new plastic fuel tank in a vehicle. In one example, during a plug-in event to recharge a battery of the vehicle, the fuel tank is isolated and the fuel pump is actuated to agitate fuel within the tank and increase fuel vapors until the plastic fuel tank becomes aged to a predetermined degree by fuel vapors generated therein. In this manner, the fuel tank is aged more rapidly, resulting in more accurate fuel level readings and less noise and vibration.