auto vs rail-carriage

auto

noun

  • An automobile. 

  • An autorickshaw. 

  • A setting for automatic operation. 

  • A car with an automatic gearbox / transmission. 

  • An automatic gearbox / transmission. 

rail-carriage

noun

  • A railroad car 

How often have the words auto and rail-carriage occurred in a corpus of books? (source: Google Ngram Viewer )