IMHO it would be helpful if adding the terms "Calculated MPG" or "On Board MPG" reading when posting. Thanks.

 

I got this info from the on board computer. Too lazy to calculate myself.

 

Had a trip LA - Tahoe through Nevada. File full tank in nevada 91 octane $3.50/gallon (in CA it almost $5 per gallon). So, CA gas is sucks. Average mileage driving through Yosemite Montanans and other non freeway roads - 25mpg! We were able to make 40o miles per tank! Whereas on CA gas 23-24mpg cruising straight on freeway.
Beside that tried to drive car aggressively, as for mileage it is worst definition eve - I was getting 13-14 mpg. In any case, I regret we did not buy 450h.

 

Now with about 800 miles on the odometer, averaging about 16mpg in an 2021 RX 350 F Sport Handling. Quite disappointing, and angry at Lexus for the dishonesty on the mpg ratings. Federal government should really investigate this.

 

There are tons of posts and threads on the lousy fuel economy of RX, going back to 2016.

It's been known and it's available information to read before buying a car to make an informed decision, i think.

 

Right. Shame on me for not googling “dishonest Lexus fuel mileage practices”. As a four time Lexus purchaser, I would have expected better, but then again, the brand IS owned by Toyota which lies when convenient for itself.

 

Without knowing your driving habits, or, how you have calculated your MPG, it is difficult to determine the source of the poor fuel economy.

I suggest you make an appointment with your Lexus dealer to have the car checked out.

 

My 2c......2017 RX350, cruise set on 70 on I95 NY to FL, routinely get 26mpg, with 16 in local traffic. I'm happy with that.

 

I KNOW it's not my driving habits. How? I have a 14 year old RX that gets about the higher mpg on the exact same types of roads, except that car requires premium gas and the 2021 requires regular. The old RX has a stated 18/23 mpg. The 2021 has 19/28 mpg. Even if I didn't have that comparison, I drive conservatively. The huge discrepancy for the F Sport has was just noted this week here: https://www.motortrend.com/features/...conomy-losers/

I reasonably expect a small discrepancy between Lexus's stated EPA figures and real world fuel economy. This much of a variance, with a final real world fuel economy that matches a 14 year old version of the car is unacceptable. Had I known what a joke the current RX 350's fuel economy was, I'd have reconsidered the purchase. I might as well drive in S++ mode all the time now, and at least enjoy the crap mpg figures.

 

I have a 2016 F Sport and get 19 around town, 30 on the open road. That's with mid tier fuel, improves slightly with top tier but haven't done the price/benefit calculation.

 

I have about 600 miles and according to the readout it has me at 24 mpg in 90% in town. 2021 f sport w handling package.

 

According to Fuelly, RX 350 F Sport owners are reporting an average of about 20 MPG. Go to your dealer to have the car checked out.
Lexus RX350 F Sport MPG - Actual MPG from 73 Lexus RX350 F Sport owners (fuelly.com)

 

16 mpg is lousy. Is that calculated by the car or by hand? What drive mode do you use most of the time? FWIW, my 2020 RX350 with 15K miles on it has averaged 22.9mpg hand-calculated over the last 3,000 miles. That's almost all in normal mode, and occasional Sport mode when I'm in the mountains. I'd call the driving mixed, with lots of 15-20 minute drives and some 3 hour highway drives. Mine is not an F Sport, but I didn't think there's a drivetrain difference unless F Sport Sport+ or ++ mode is used.

 

Thanks for that pointer to the fuelly app. I signed up. 20 mpg is about what I would have expected for the F Sport. I'm taking the 1,000 mile break-in guidance seriously so I never drive it in Sport modes. 16mpg is just ridiculous. And I'm hand calculating that.

 

I was trying to find out how traffic light stops impact my MPG (I know they do but curious to what extend) and instead came across this - turns out the faster you go above 50mpg, the more "fuel penalty" you pay. And it seems pretty significant. According to www.fueleconomy.gov, if you go 80Mph on a highway (specifically in RX 350), you are burning 50% more fuel than if you went 50Mph.. pretty crazy. See attached pic - I entered $2.90 cost of a gallon I pay here locally and the chart is showing how much more I'm paying (hypothetically) for gas when going faster than 50Mph. At 80Mph it's almost 50% increase. Of course cost of the gas is the same, it simply shows drop in efficiency.