Interesting thread. I never used Premium in my 2022 RX450h Luxury Package, Atomic Silver, Black, 20" Michelin Cross Climate 2
I run in normal mode, rarely drive over 65 mph and have never seen less than 31 mpg
I live in Northern Kentucky where it does get hot in the summer but that does not seem to have much effect
Why run the Premium gas when the car runs fine on 87 Octane?

 

I am just doing what the owner's manual states. Also, to protect my investment, I would like this vehicle to last a very long time. I usually gas up about once every 5 weeks. Not a big deal.

 

2020 RX450h fill up at 24,112 miles 11/24/25. Traveled 362.9 miles, 70% local, 30% highway 70+ MPH. Weather mostly 40F to 60F.
28.7 mpg calculated. The RX said 28.6 mpg. Filled up with Sam's Club Premium 93 Octane.

 

2020 RX450h fill up at 24,452 miles 12/16/25. Traveled 340 miles, 70% local, 30% highway 70+ MPH. Weather mostly 40F to 50F.
27.3 mpg calculated. The RX said 27.3 mpg. Filled up with Sam's Club Premium 93 Octane.

 

2019 RX 450h F-Sport, averaging 28-30 MPG in normal or sport mode.
Initially I was getting lousy mileage in city driving until I discovered this hack -- from stop, accelerate quickly UP TO 40mph (not higher). Repeat at the next stop sign or red light.
IMO the eco mode is a joke, it does nothing for the mpg. Mostly I use sport/sport+ mode.
I wish the EV mode would last longer, it's such a neat feature on a hybrid! (I believe the Mercedes 48-volt mild-hybrid system can also run EV-only for a short duration.)

 

2020 RX450h fill up at 24,814 miles 01/19/26. Traveled 362.4 miles, 100% local, 0% highway. Weather mostly 40F to 50F.
28.3 mpg calculated. The RX said 27.8 mpg. Filled up with Sam's Club Premium 93 Octane.

 

2020 RX450h fill up at 25,148 miles 03/03/26. Traveled 333.1 miles, 100% local, 0% highway. Weather mostly 40F to 70F.
27.7 mpg calculated. The RX said 27.7 mpg. Filled up with Sam's Club Premium 93 Octane.

 

2020 RX450h fill up at 25,967 miles 05/25/26. Traveled 398.8 miles, 100% local, 0% highway. Weather mostly 70F to 85F.
29.7 mpg calculated. The RX said 29.9 mpg. Filled up with Sam's Club Premium 93 Octane.

 

The most I'm getting is 28 mpg.
Still better than 19-20 on my old RX350