Is car an collective noun or a proper noun or a common noun?

The noun 'car' is a common noun, a singular, concrete noun, a word for any car of any kind.

A proper noun is the name of a specific person, place, or thing; for example:
  • Car Street, La Crosse, WI or Car Street, Youngstown, OH
  • Cable Car Coffee Shop, South San Francisco, CA
  • Car and Driver Magazine

A collective noun is a word used to group people or things taken together as one whole.
The collective noun for cars is:
  • a fleet of cars