Should Car Windows Be Left Slightly Open in Summer?
3 Answers
In summer, car windows should not be left slightly open as it poses a safety risk. Relevant information is as follows: Categories: Car windows are typically divided into four types—front and rear windshields, ventilation windows, heat-insulating side windows, and sunroofs. Function: The front and rear windshields of a car usually use curved glass that enhances visibility while maintaining an aesthetic appeal. In sedans, these are also referred to as front and rear windshield glass. To facilitate natural ventilation, some cars are equipped with triangular ventilation windows on the doors. These triangular windows can rotate around a vertical axis, with the front part turning inward and the rear part outward, creating a vortex of air that circulates around the window.
I've tried leaving the car windows slightly open when parking in summer and found the effects quite mixed. When parked in direct sunlight, a small gap does allow some hot air to escape, keeping the interior about 5-6 degrees cooler than with fully closed windows. However, you must be extra cautious about security - once I forgot to lock the center window gap and returned to find a sparrow had entered, leaving bird droppings all over the seats. Also, sudden rain can easily pour in through the gaps. My suggestion: if parking within sight and with reliable weather, leave about 2cm gap; for open parking or uncertain weather, it's better to use a sunshade and lift the wipers to prevent aging.
Let's talk about fuel efficiency from the perspective of driving with windows open. Whether it saves fuel depends on the speed: in city traffic jams, opening windows instead of using the AC can indeed save some fuel—I've tested and found savings of around 7%-10%. However, on highways, it's the opposite. When speeds exceed 80 km/h, open windows increase wind resistance, leading to 12%-15% higher fuel consumption compared to using the AC. Especially when opening diagonal windows, the cabin gets a buzzing noise, which can be uncomfortable for the ears during long drives. My usual practice is: at low speeds, open one rear window slightly along with the front window about a third—this provides good airflow; on expressways, close the windows and use the AC in external circulation mode, setting the temperature at 25°C for the most economical operation.
