What results in increased fuel consumption of your car?

Your answer is correct because both having a roof rack or ski rack on your car (even when not in use) and carrying unnecessary heavy objects increase air resistance and weight, which makes the engine work harder, leading to higher fuel consumption. In contrast, excessive tire pressure does not directly increase fuel consumption; in fact, slightly higher tire pressure can sometimes reduce rolling resistance. Therefore, to save fuel, it is advisable to remove roof racks when not needed and avoid carrying unnecessary loads.