auto vs automatic transmission

auto

noun
  • An automatic gearbox / transmission. 

  • An autorickshaw. 

  • An automobile. 

  • A setting for automatic operation. 

  • A car with an automatic gearbox / transmission. 

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. 

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