Do Sunshades Actually Keep Your Parked Car Cooler?

It’s common sense: a sunshade in your windshield should block heat, just like blinds in a home. But how much cooler can it really make your car? A 1988 study by the University of Central Florida’s Solar Energy Center tested two identical Toyota Tercels parked at Cape Canaveral under the Florida sun. Without any shade, the interior hit 150°F, and the dashboard neared 200°F.

A simple cardboard sunshade behind the windshield cut interior temps by 15°F and slashed dashboard temps by a dramatic 40°F. Foil-backed shades performed even better, dropping interior temps by an extra 3–5°F and dashboard temps by another 6–11°F. So yes, sunshades work—but they’re not the best option. An exterior windshield cover is more effective.

A 2012 study from Malaysia found that a basic nylon sunshade in the front windshield reduced dashboard temps from 189.5°F to 156.9°F—a drop of 32.6°F. Meanwhile, Germany’s ADAC, Europe’s largest automotive club, tested multiple passive cooling methods in a 2026 study. The most effective solution was a partial exterior car cover, which dropped internal temps from 127°F to 109.4°F. An exterior reflective sunshield was nearly as good, cutting temps from 127°F to 113°F.

Placing the same shield inside the windshield only brought temps down to 120°F, while a plain white cloth did almost nothing, allowing temps to rise to 122°F. Color matters too. ADAC found that a black car’s surface reached 149°F under midday sun, while a white car’s surface stayed at 111°F. Inside, the black car hit 127°F compared to 118°F in the white car.

A 2011 study by Lawrence Berkeley National Laboratory showed that cooling a silver car from heat to a comfortable 77°F took 13% less energy than cooling a black car. Parking in the shade is another smart move. The U.S. Department of Energy warns that running A/C at max can slash fuel economy by up to 25%.

Oak Ridge National Laboratory advises parking in the shade to keep cabin temps lower and reduce A/C strain. And never underestimate the danger of leaving children in parked cars. Consumer Reports found that even at a mild 61°F outside, a car’s interior can reach 105°F within an hour—hot enough to cause deadly heatstroke. Over half of all child hot car deaths have occurred this way.

Bottom line: sunshades help, but exterior covers and parking in the shade are far more effective. Always prioritize safety, especially when it comes to kids.