Climbing into your vehicle during a heatwave can be a deeply unpleasant experience. The windows on every side of the car allow sunlight to flood in, warming up the interior while hot air becomes trapped inside, essentially transforming it into a compact greenhouse . Fortunately, most modern cars feature air conditioning, meaning you'll only need to endure the discomfort for a few minutes before it cools down, after which you won't want to get out. But what's the quickest and most efficient