Hey, when your left with the collection of polygons, select them all under the objects mode and goto
Polygons > Combine.
It seemed to have worked for me, after they were combined, i had 2 seperate objects. There must be a combine on extract options somewhere!
I have this problem too, exactly the same.
Thank you so much for the detailed post because it explains everything.
We are being left with a collection of faces, yet on the tutorial his extracted faces automatically turn into an object. When he extracts his bumper, it turns into a single selectable object. I know the guy above aint doing it wrong either because i have redone it 2 times.