automatic transmission vs motorcar

automatic transmission

noun
  • A vehicle transmission which shifts gears automatically in response to vehicle speed and/or load, and does not require any driver input to manually change gears under normal driving conditions; an automatic gearbox. 

motorcar

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

  • A self-propelled railway vehicle 

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