* Less ventilation: Trunks typically have fewer or smaller vents than the passenger compartment.
* Darker interiors: Trunks often have darker colored interiors which absorb more heat.
* Direct sunlight: The trunk's larger, often glassless surface area can absorb more direct sunlight than the backseat windows, which often have some level of tinting or UV protection.
While the specific temperature difference can vary greatly based on factors like car color, window tinting, ambient temperature, and how long the car has been sitting in the sun, the trunk generally gets significantly hotter.
