landau vs passenger car

landau

noun
  • A type of lightweight, four-wheeled carriage in which the front and back passenger seats face each other. 

  • A style of automobile based around the design of landau carriages. 

passenger car

noun
  • A motor vehicle designed to carry (a few) passengers; a motorcar. 

  • A railroad car designed to carry passengers. 

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