Your fuel tank capacity is not just for your fuel. Whenever you visit the gas station to refill the fuel. You fill the car up beyond its capacity which leaves no space for fuel vapours, overtime this can lead to damage in emission control system of the car. Also, at least keep 25% of the fuel in the tank, since the fuel in your fuel tank also helps in cooling the engine. Emptying the tank completely can lead to overheat issues in the engine. Follow @getoneinsure for more such car tips and tricks