hardtop vs touring car

hardtop

noun
  • A car with such a roof. 

  • The removable rigid roof of a convertible or sports car. 

  • An indoor cinema with a roof, as opposed to a drive-in. 

touring car

noun
  • A large open car seating four or more people and having a folding top. An automobile designed for touring; specifically, a roomy car, not a limousine. 

  • A type of race car based on a modified production car, that is a sedan or saloon car. 

How often have the words hardtop and touring car occurred in a corpus of books? (source: Google Ngram Viewer )