automobile vs motorcar

automobile

noun
  • A type of vehicle designed to move on the ground under its own stored power and intended to carry a driver, a small number of additional passengers, and a very limited amount of other load. A car or motorcar. 

adj
  • Self-moving; self-propelled. 

motorcar

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

  • A self-propelled railway vehicle 

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