To ensure **good visibility** while driving, cars must have at least **two rearview mirrors**. These mirrors allow the driver to see what is happening on the sides and behind the vehicle, which is essential for safety.

- **Left rearview mirror**: It is mandatory to have a rearview mirror on the left side of the car. This mirror is crucial for observing the traffic approaching from that side.

- **Interior rearview mirror**: It is also mandatory to have a rearview mirror inside the car, located in the central part, above the front windshield. This mirror allows the driver to see what is happening directly behind the vehicle.

- **Right rearview mirror**: Although it is recommended, it is not mandatory to have a rearview mirror on the right side of the car. However, if sunshades are installed on the rear windows, then it is necessary to have this mirror.

Therefore, a car must have at least **two rearview mirrors**: the left and the interior.