Rolls-Royce vs ne plus ultra

Rolls-Royce

noun
  • A car made by this manufacturer. 

  • Anything that is the best of its type; the best quality product possible. 

name
  • any of several British companies that make motor cars, aero engines, etc. 

ne plus ultra

noun
  • A prohibition against proceeding further; an insuperable obstacle or limiting condition. 

  • The highest, ultimate point of achievement which can be reached; perfection. 

  • The perfect or most extreme example of its kind; the ultimate. 

How often have the words Rolls-Royce and ne plus ultra occurred in a corpus of books? (source: Google Ngram Viewer )