power car vs steam train

power car

noun
  • A vehicle equipped with machinery for supplying heat or electrical power to other parts of a train. 

  • A vehicle that propels, and commonly also controls, a passenger train or tram, often as the lead vehicle. 

  • Antonym: trailer car 

steam train

noun
  • A train pulled by a steam locomotive. 

How often have the words power car and steam train occurred in a corpus of books? (source: Google Ngram Viewer )