Most 3D games don't _render_ objects that you can't see. They still must simulate their actions each tick so that they will be in the right place when you can see them.
I imagine Grand Theft Auto doesn't simulate any cars that are more than slightly farther than the render distance.
I've seen videos showing that Cyberpunk 2077 will even not simulate things just because they left your view. People and cars will just disappear after you turn around for a second.
