How to pass main object reference to its low level modules in c++

When ever I create my main(Car) object, internally its creates low level modules one by one.

I am referring some function in main object in all internal object

Currently I am passing main object through function(Setter function in all class)

Some how I don't feel its good.could you suggest me some good design.

example:

Code:

---

car mainobject
 
   grid object                mainobject->getFIleName()
      vertex oject            mainobject->getFIleName()
          sub object1         mainobject->getFIleName()
          sub object2         mainobject->getFIleName()
 
   triangle object             mainobject->getFIleName()
        vertex oject            mainobject->getFIleName()
          sub object1           mainobject->getFIleName()
          sub object2            mainobject->getFIleName()
 
   canvas ojbect                mainobject->getFIleName()
 
   mesher oject                 mainobject->getFIleName()
         obj1                          mainobject->getFIleName()
         obj2                           mainobject->getFIleName()
         obj3                             mainobject->getFIleName()

---

I though of have static class. from static class I will get main object but i need to create multiple instance of car so I cant use static class

If you have multiple instances of that class then passing the correct instance to functions or other objects sounds like a good idea.

Cheers,
_