Think about the heat in your car!
Every year cats are left alone in hot cars, this can very quickly result in a death trap for the cat left behind. The heat in the car rises incredibly quickly and is much hotter than outside.
In summer, therefore, one basic rule applies above all when it comes to cats and cars - the cat should never be left alone in the car! Leaving the car window open does not help, as it does not provide sufficient ventilation to lower the temperature in the car. This applies whether it is sunny or shady.
In the table above you can see how much warmer it is in the car than it is outside. Always think twice before taking your cat for a ride in the car in summer!