hardtop vs two-seater

hardtop

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

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

  • A car with such a roof. 

two-seater

noun
  • A vehicle with seats for two people (a driver or pilot and one passenger) 

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