Do Sunshades For Car Windshields Actually Work & Keep Vehicles Cooler When Parked?

There are few more uncomfortable feelings than getting into a car after it sat under direct sunlight for hours on end. Thus, there are multiple ways to cool down your car throughout the hot summer months, with one of the most well-known being the sunshade. These simple devices sit behind the windshield, supposedly deflecting the sun's rays and minimizing heat buildup inside the cabin. In practice, though, do these shades actually make a difference in your car's temperature? According to those who've put them to the test, they can make a noticeable difference on a few fronts.

For instance, Popular Mechanics ran a three-day test comparing car temperatures with and without the shade when left in around 90-degree heat. Between 15 and 90 minutes, results showed the shade typically reduced cabin temperature around 10 to 20 degrees. Meanwhile, another study from the Department of Mechanical Engineering at Universiti Teknologi PETRONAS reported a 26% decrease in dashboard temperature and a 27% decrease in air temperature when using a sunshade. The Florida Solar Energy Center's research also found shades to be effective at reducing temperature. Conventional cardboard shades brought air temps down by around 15 degrees and dashboard temps down by roughly 40 degrees. Foil-backed shades reduced both temperatures even further.

On the whole, a sunshade seems like a good idea for cooling a car on a hot day. As it turns out, you can get even more from such a car accessory by making minor adjustments.

Setting up a car sunshade might seem like a simple task, but there are a few things to get right to ensure it does its job effectively. For one, the foil side needs to face outward, allowing it to adequately reflect sunlight and deter heat buildup. You also want to ensure it's positioned so that it covers as much of the windshield as possible; this way, it can deflect as much sunlight as possible. Make sure it's secured in place, too, using any ties and loops around the rearview mirror or simply by folding down the sun visors. The last thing you want is for it to dip over time and eventually fall off.

Additionally, a car sunshade can come in handy in the wintertime, too. Along with an underused feature that goes a long way in warming a car up, a sunshade can help keep heat inside the cabin — assuming you have the type with one reflective and one non-reflective side. All it takes is flipping the sunshade to the opposite side so that the reflective side faces the inside of the car. The other side will absorb heat rather than reflect it, raising the cabin's internal temperature without relying on the heating system.

Though sunshades are far from the most technically complex or elaborate car-improvement accessories out there, they seem to help considerably. They can keep vehicles a bit cooler in the scorching sun, or draw in heat once the bitter winter cold rolls in.