Question about box input "ontology" SAM2

Hi,

I am not sure if this is the correct place to post.

I want to be able to detect the rear-end of the car, can the ontology only go as far as just objects such as "Car" or could i go so far as to say "rear end of car", if not can i just use key points and then do it that way until it is trained on yolov8. I want to essentially detect the rear-end of vehicles and then track them.

Many thanks for any replies!
Kind regards,
-Jarrad