Why is the inside of a car hotter than the outside on a summer day?

The greenhouse effect keep the heat in and it get humid making it feel hot.

The inside of a car is hotter than the outside because of conduction and heat radiation. Cars are mostly made out of metals, and metal easily conducts heat. So, the inside of the car becomes hotter as the heat radiation is trapped inside of the compacted space of a car, resulting in a temperature hotter than the outside. XD