I realize fuel efficiency is not just about the engine, but the engine is surely a key factor so I hope this question is accepted here:
10~11 years ago if someone wanted a fuel efficient car in a certain class, they would have landed on options like the Toyota Prius or Lexus CT. (they have a second engine but only consume gasoline, meaning their efficiency is simply distance/liter).
I was looking into new car options today, figuring that a decade is a fair amount of time to find improvements, and was really surprised that most new cars do not even advertise the efficiency that these cars promoted 10 years ago.
I considered that perhaps definitions got stricter, so instead of looking at advertised efficiency I decided to compare the actual efficiency of these 2011&2012 cars, to the actual efficieny of several other cars via spiritmonitor.de
I just checked a few cars that came to mind, but in the end pretty much any car appears to be less efficient today than these models were 10 years ago. Even the Lexus UX cannot keep up.
Hence my question: Have gasoline engines (or cars) really not gotten more fuel efficient in over a decade?
If so, why?! Or am I looking at it in the wrong way. (For instance, the engines got more efficient, but safety regulations or other requirements led to less efficient cars overall).