Separating similar object in an image - opencv python

I am trying to detect the objects in an image which look similar to the reference image. Here is how i'm trying to accomplish it:

Here is the sample Image:

and here is the image with SURF keypoints:

The rectangle is drawn based on Clustering method like "Hierarchial Clustering".

The main problem is, in this case it doesnt detect the objects individually, it detects everything as one object.

Is there a way to seperate these keypoints, so as to detect each vehicle seperately? Is this a good way to detect objects or if there is a better way please suggest.