The Tesla Model S fuel efficiency is between 100 and 110 combined mpg.
The official statistics released by Tesla for the 2022 Model S state that this car gets up to 124 city / 115 highway miles per gallon. For older Model S cars, the average combined mpg is closer to 110.
When you look at data submitted by real Tesla owners in real operating conditions, the Tesla Model S fuel efficiency is closer to 100 combined mpg.
Of course, your fuel efficiency depends on which Model S you get (i.e., the Long range, Standard-range, 100D, or Performance).