Even if it has taken a short break in many parts of Germany at the moment, summer will soon be back with plenty of sunshine in its luggage. However, the strong sunlight in a parked car can quickly lead to temperatures above 60°C, making a forthcoming car journey unbearable.

The German Automobile Club (ADAC) has therefore investigated what helps best against direct sunlight and thus against heating up inside the vehicle. Seven identical Dacia Dusters were subjected to a heat test.
Four of them were equipped with different sun protection measures.

In addition, a vehicle with tinted side and rear windows, a white vehicle and an unprepared car were used as a reference. The temperature development was recorded for around four hours over midday.

The accessories tested: a tarpaulin for the window surfaces all around (semi-garage), a reflective sun protection film for the outside, a white fabric cloth to rest on the dashboards and a reflective sun protection screen for the interior.

The reference vehicle without any accessories heated up to 53 °C. The tarpaulin (half-garage) showed the best effect (43 °C), as the interior is protected all around from the sun's rays. The sun protection film on the outside reduced the interior temperature to 45 °C. When fitted inside, the reflective sunshade (49 °C) and the white cloth on the dashboard (50 °C) had the least effect.

The situation was similar with window tinting from the B-pillar. They only reduced the interior temperature by two degrees. Nevertheless, they prevented the rear seat surfaces from heating up too much. Without window tinting, the temperature there was 57 degrees, with tinting it was only 48 degrees.

When comparing the white vehicle with the black one, it became apparent that the colour makes for a slight difference inside the vehicle. While 65°C were measured on the paint surface of the black car and only 44°C on that of the white car, the interior of the white car heated up five degrees less than the black one.

General finding: Heated dark surfaces contribute more to high interior temperatures than the vehicle paintwork itself. Air and surface temperatures differ considerably. Steering wheel and dashboards get hot to over 70 degrees, posing a risk of burns to the skin. Any sunshade accessory will effectively reduce surface temperatures. The steering wheel stays 14 to 26 °C cooler.

Animals and children should never be left in the car at higher temperatures. Electronic devices also do not belong in the vehicle. The steering wheel and dashboard can be covered to prevent excessive heating. Child seats can also be protected from direct sunlight with a light-coloured cloth. The ADAC advises you to buy sun protection at a specialist shop and to seek advice.