Do you think that turning on your car air conditional while driving increases your fuel consumption? Well the answer is yes! Like every other device in your car, the air conditional draws energy from the engine which automatically increase load on the engine, therefore increasing fuel usage. When your car is running, it makes use of energy supplied by the alternator which comes from the engine. When the compressor runs, more pressure is put on the engine which gives out more energy. With the car ac on, the car actually burns more gas than with the ac off. The bigger question however is, which consumes more fuel, driving with ac on or driving with windows down? Like state above, the air conditional when on, draws power from the engine, depending on the car make and brand, the amount of power used u the ac varies. Rolling down the windows on the other hand burns more fuel than we actually realize! The average car driver does not have the idea of this. With the windows down, a car becomes less aerodynamic. The air that gushes in through the window causes additional resistance or drag, thereby increasing the car’s resistance. Increased resistance means that the car has to work harder to maintain its speed, therefore putting more strain on the engine which automatically burns more fuel. In 2014, the Society of Automobile Engineers (SAE) conducted a research by testing a car in both a wind tunnel and on a desert tract in Arizona, using a full sized sedan and an SUV. The study showed that driving with the window rolled down was actually more fuel consuming while especially driving faster than 50 – 55 mph, fuel efficiency dropped by a whopping 20%, but only 10% when the air conditional was on. SAE recommends driving with your window down if you are driving in city street that does not require speeding, however when in a highway, the drag produced by rolling down your window exceeds the efficiency drop by keeping windows rolled up and ac on. For better fuel economy, windows should be rolled down while driving in your neighbourhood, traffic and low speed areas while ac should be used when driving on highways Anf express road.