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Do Sun Shades Actually Keep Cars Cool During Summer?

Do they really reduce that hot box effect in cars, or are they all just part of some big marketing scheme?
ByRudie Obias|
They can make cars look a bit cooler in the looks department, too.
They can make cars look a bit cooler in the looks department, too. | Thomas Winz, Photodisc Collection, Getty Images

Whether you’re going to the beach or the park for a picnic this summer, chances are that you’re going to need to park your car ahead of all that fun in the sun.

But the sun that you’re enjoying is the same sun that’s also increasing the temperature inside your vehicle. So when you return, it’s hot, sticky, and humid inside. You can even burn yourself if you’re not too careful. In fact, the interior can rise in temperature up to 200°F, depending on the day’s weather. That’s as hot as an oven.

Why does the temperature in your car get so hot on the inside, even if the temperature is cooler outside? If you’ve ever wondered how that happens, and whether or not sun shades actually keep cars cool, keep reading on for more insights below.

  1. The “Greenhouse Effect” in Cars: Is It a Myth in the Summer?
  2. Can Sun Shades Help?
  3. How To Make Cars Cooler in the Summer

The “Greenhouse Effect” in Cars: Is It a Myth in the Summer?

Sunlight has a broad spectrum of light wavelengths, including ultraviolet, visible, and infrared. When sunlight enters a parked car, specific wavelengths are able to pass through, such as visible light, while others, like ultraviolet and infrared, are trapped inside. These wavelengths become trapped because of the thick glass of the windshield, windows, and rear window.

It’s the same reason why a greenhouse is warmer on the inside compared to the temperature of the air outside. The sunlight is trapped inside and absorbed by the seats, dashboard, steering wheel, and other surfaces. This can increase the wear and tear on your car’s interior, though, which can lower its resale value over time.

Can Sun Shades Help?

Yes, sun shades (also known as sun visors) have been shown to significantly reduce temperatures in vehicles by up to 25 percent, compared to not using them at all. It’s also an inexpensive solution, with sun shades available for around $10 to $30, depending on size, on online retailers like Amazon and Walmart. But overall, sun shades can provide some peace of mind, especially if you’re worried about leaving a window cracked open while you’re away, but there are a few more specific tips and tricks that may be helpful, which we'll break down below.

How To Make Cars Cooler in the Summer

The easiest and most cost-effective way to prevent your motor vehicle from heating up come summer is to crack a window open about one to two inches after you park. With this simple move alone, you could reduce temperatures by up to 30 degrees, as it offers a means of escape for those ultraviolet and infrared wavelengths from the sun.

Before you exit the car, consider turning the steering wheel 180 degrees, so the top half of the wheel won’t be in direct sunlight. When you return, the top half will be cooler to the touch. Additionally, you can use beach blankets to cover your seats, keeping them out of the sun.

However, one of the best ways to keep cool when parked is to use a trusty sun shade over the windshield. This can help to block most sunlight from entering. As the shades are made from reflective materials, such as mylar or aluminum foil, and feature layers of nylon or polyester for insulation and durability, they prevent sunlight from being absorbed into your vehicle’s interior.

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