brougham vs driver's compartment

brougham

noun
  • An automobile, a sedan without a roof over the driver's seat. 

  • A four-wheeled horse-drawn carriage, designed in 1839. It had an open seat for the driver in front of the closed cabin for two or four passengers. 

driver's compartment

noun
  • Synonym of cab (compartment at the front of a truck or train for the driver). 

How often have the words brougham and driver's compartment occurred in a corpus of books? (source: Google Ngram Viewer )