Gas cap is a crucial component in any automobile as it covers the fuel tank and prevents any contaminants from getting into the fuel system. There are several synonyms for a gas cap, including fuel cap, petrol cap, filler cap, tank cap, and gas tank cover. These terms refer to the same part of a vehicle that seals the fuel inlet and prevents gasoline evaporation. It is essential to ensure that the gas cap is always correctly installed, otherwise, the fuel efficiency will suffer, and the vehicles' emissions will increase. In summary, while there are different synonyms for the gas cap, its function remains the same- to ensure a safe and efficient fuel system.