How do you fix gas cap door on Mercury Mystique?

To fix the gas cap door on a Mercury Mystique, start by inspecting the door and its hinges for any signs of damage or misalignment. If the door is misaligned, gently adjust it back into place. Check the latch mechanism to ensure it is functioning properly; if it's stuck, clean it and apply lubricant. If the door is broken, you may need to replace it with a new one, which can typically be found at an auto parts store or through a dealership.