automobile vs motorbus

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. 

motorbus

noun
  • A motorised bus, or coach. 

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