cabriolet vs hackney cab

cabriolet

noun
  • A light two- or four-wheeled carriage with a folding top, pulled by a single horse. 

  • An automobile with a retractable top. 

hackney cab

noun
  • A hackney carriage, a carriage pulled by a hackney horse, available for public hire. 

  • A motorised vehicle available for public hire; a black cab. 

How often have the words cabriolet and hackney cab occurred in a corpus of books? (source: Google Ngram Viewer )