Aerodynamics/wind resistance are your enemy at higher speeds. And they grow out of proportion to the increase in speed. There is a big difference between 55 and 60, 60 and 65, etc. So at 75 mph you are spending a lot of energy just pushing a lot of air out of the way. I realize you have data points at lower speeds too so I don't really know what's going on there, but FWIW if I'm going 75 I'll hit around 27-28 mpg too. I think the car's sweet spot is between 45-55 mph. My commute is 70% at that speed, and the car is super efficient in that range (for a big SUV that is). But those are speeds where wind resistance is minimal. I've read the drag coefficient is .34 - which is not super good. Basically in the category of a small van.

 

Laws of Physics do not ignore what type of fuel a vehicle uses. A big SUV will have to fight the wind resistance A LOT more than a low car.

I average 9 L/100km (26 MPG) in my RX 350 If I can keep my speed on highways below 110 KM/h (~65 MPH)

Days that I drive the ES300h on the exact same commute and same speeds I average 4.7 - 5 L/100 km (47 - 50 MPG)

22 RX uses previous Gen Hybrid that is not very efficient at higher speeds. The new Gen Hybrid adds more highway efficiency, so I would expect the 23 RX 350h to be better than 450h.

 

I just got back from a 1200 mile round trip in my 450h. I basically had four 300-mile legs where I used 87 on half the legs, 91 on the other half (since premium was cheaper where I was going). Speed was usually 75 mph. Interesting on 87 I got 25-26 mpg, on 91 I got 28.

 

2020 RX450h fill up at 9,491 miles 11/3/22. Traveled 413.2 miles, 100% city short trips mostly 14 miles each way, 0% highway, weather mostly 60F to 75F.
31.9 mpg calculated. The RX said 31.6 mpg. Filled up with Sam's Club Premium 93 Octane.

 

I can only dream of getting that sort of mpg. Mine is closer to 23.5 US mpg or less with my typical suburban driving, on 95 octane unleaded gasoline.
I think it may have something to do with my slightly higher engine oil viscosity (SAE 5W-30 instead of the recommended 0W-20)

My mpg figure will probably get worse after today, when I switch my tyre size from the stock 235/55x19" to a non-standard 245/55x19" - the slight increase in rolling diameter will make the true mpg worse.
The main reason for going slightly wide is in the faint hope that the tyre might better protect the rims from getting kerbed. Let's see how it goes!

I also went with a more aggressive tyre pattern (Pirelli ATRs) so this will also have an impact on fuel economy. So double whammy for me due to size and tyre pattern change.

 

2020 RX450h fill up at 9,915 miles 12/17/22. Traveled 423.8 miles, 100% city short trips mostly 14 miles each way, 0% highway, weather mostly 40F to 55F.
30.4 mpg calculated. The RX said 30.0 mpg. Filled up with OT Premium 93 Octane.

 

2022 RX450hL model drove 12,000 miles so far and had the first 10k maintenance last month.
Before the first service, I could easily get 30+ MPG thanks to my daily commute traffic, however, ever since then (after service) it dropped dramatically down to 25~26 MPG.
Does anyone have any clue?

 

25 - 26 mpg is normal. Anything over that is just a bonus. A few above are getting great numbers but the Fuelly app shows & most dealers will tell you that those numbers are not the norm for most people. Toyota notoriously overstates their mpg ratings & few actually achieve Toyota’s stated numbers. I would much rather be pleasantly surprised at great mileage vs. being disappointed. It is what it is.

 

Did the temperature drop where you live, that can cause it to drop.

 

We usually get about 31 MPG or so when the temps are running at least 45 degrees F or so - in city/suburban driving. Lately our temps have been way down in the teens and 20s, and our 450h is currently showing 28 on the dash. The dash normally reads a bit optimistic, so we are likely around 26 or 27 right now, which is very typical of hybrids in cold weather. If your temperatures haven't dropped, then I would certainly wonder if something else isn't going on.

 

Ironically, when I filled up this week the mileage on the dash was identical to the calculated mileage. I calculated 28.3 MPG in this cold weather - so I'm satisfied with that. I should point out that it is rare for the two figures to agree as the dash usually reads about 1.5 MPG better than manual figures

 

Two years now on my 2021 450h. Second year MPG was slightly higher than the first year (36.28 v. 36.19). I drove about 400 fewer miles due to one less road trip. However, the overall mix of highway (~75%) versus city (~25%) driving remained pretty much the same. The car's MPG really shines on long highway drives, and in warmer weather. Short city trips - especially in cold weather - depress MPG. One other note. I chucked the original Bridgestone's in favor of Michelin Cross Climate 2's after about 10 months (November 2021). Obviously, this had no negative effect on MPG, and, I have not noticed any change in tire noise which remains pleasantly muted.

As I am retired, I have no daily commute. I can often consolidate errands to insure I am driving more miles with the ICE fully warmed up. I avoid driving in very cold weather whenever possible.

 

2020 RX450h fill up at 10,256 miles 02/13/23. Traveled 340.8 miles, 100% city short trips mostly 14 miles each way, 0% highway, weather mostly 30F to 50F.
27.2 mpg calculated. The RX said 27.3 mpg. Filled up with Sam's Club Premium 93 Octane. My RX does not like the colder weather, I guess longer time to warmup. Still very happy with the mpg.

 

No, hybrids don’t perform as well in cold weather. I just filled my 450h yesterday. It only calculated to 24.3 mpg. Worst tank ever. Temps between about 10F to 35F. All city, and unfortunately all short trips on this tank. Bad combination for a hybrid.

 

I find that in my ESh the heater and AC have huge impact to MPG.

If HVAC is on then the engine needs to run to keep the cabin at desired temperatures hence the fuel economy takes a dive.

I find that when the car moves warm air still comes in the cabin when when HVAC in off.