automobile vs motor vehicle

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. 

motor vehicle

noun
  • Any land-based means of transportation in the form of a machine that operates primarily through a motor consuming fuel in order to provide power to rotate the tires. 

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