Setting up permissions My cars data is as the following:

id    make        no         parent
1     bmw         NULL          0
2     bmw         bmw987        1
3     bmw         bmw654        1
4     ferrari     NULL          0
5     ferrari     ferrari987    4
6     ferrari     ferrari654    4


(Note: I am using two tables for above data. This is just to get an idea of data.)

I am creating permissions to book cars as:


Book bmw; the user will have permission to book bmw987 and bmw654 means
children of BMW  
book bmw987; the user will have permission to book bmw9987 only.
Book ferrari; the user will have permission to book all Ferrari cars.


In my car booking portal, I have 100's of cars and many makes. When I used hook_permission() and loop through all available cars to create book permission on each car, it pollutes my permission page (admin/people/permission) and believe me handling these many permission will faint Admin.  

Is there any other alternative to handle such huge permission?
I think you should try something like this 

function mymodule_menu() {
  $items['example/car/%'] = array(
    'title' =&gt; 'Example RSS feed', 
    'page callback' =&gt; 'example_feed', 
    'access arguments' =&gt; 'mymodule_abc_view', 
    'type' =&gt; MENU_CALLBACK,
    );
    return $items;
}

function mymodule_abc_view() {
    return 'TRUE after checking something';
}


your URL should pass the car id or something to check the permission.