From my post in another tread..
"My 2019 RC300h averages 43 mpg in everyday driving around country roads and urban commutes.
When long distance high speed drives on motorways this average drops to mid to low 30's
The RC300h hybrid system is definitely a glorified Stop/Start and in that respect performs faultlessly in town/urban traffic. Let it loose on open roads and it is basically a traditional 2.5ltr petrol engined car, with an extra boost from the traction battery when needed."
In contrast my 2005 2.7ltr CDI Mercedes would happily return 50+ mpg at the same sort of speeds but only achieve low 30's around town, in the summer. My 5.5ltr supercharged AMG would manage 27mpg on the motorway and creep into the higher teens around town.
The Lexus hybrid is really tuned to stop-start town driving but with the new generation UX and ES breaking that mould with significantly better high speed economies