boxcar vs motorcar

boxcar

noun
  • An enclosed railway goods wagon, typically with a sliding door. 

verb
  • To reduce to a boxcar function. 

motorcar

noun
  • A self-propelled railway vehicle 

  • An enclosed passenger motor vehicle, a car, powered by an engine. 

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