DavidGilly

Thanks for the reply. After extensively looking through about 100 pages on the forum, the majority seem to say that premium truly is not required and doesn't affect mileage, performance or warranty in the hybrid, so for my comparison I am assuming regular fuel being used for both.

DocRock

My wife has a 2020 RX 350 and I have a 2021 RX 450h. Our ratio of highway to city miles is roughly the same for both. Accounting for differences in driving styles (my wife has a heavier foot and I am an unapologetic hypermiler). I would estimate that my 450h gets about 10 MPG more than her 350. The big difference is city driving where I estimate the MPG difference is roughly 13-14 MPG. On the highway, I get outstanding MPG mainly because I drive at the speed limit (typically 55-60 MPH on the highways we drive).

Cold weather is an issue. Note the 450h traction battery is underneath the rear seats, so when the cabin temp warms up to a comfortable level, the traction battery will be quite efficient. But the ICE is also affected by cold weather. One way to combat the effects of cold temps is to avoid short trips whenever possible. I am retired, so I do not have a daily commute. During the winter, I try to combine as many errands as possible into one trip. I will say I have found that once the air temp gets to 50 or higher, my 450h is a real champ at fuel economy. If the air temp is in the 20-50 degree range, not so much.

You can check out my mileage here by clicking the Fuelly link below.

lgb0250

At this stage in life it is just much easier for us to follow the manuals suggestions. We all obviously paid a fair amount of money for a luxury vehicle. I’m not going to skimp on gas to save a few penny’s here and there. What I find funny though is that my high performance 5.0L engine in my Mustang is recommended for 87 octane by the manufacturer. Well, I choose to run 93 in it also. But, I’m old school and believe it will thank me every time I choose to kick it in the rear! I just think a high performance engine should be treated like one. To put 87 in a vehicle with over 450 bhp is just a non starter for me.

jrobe

2020 Rx450h Fuel type

Unleaded gasoline only

Octane Rating

91 (Research Octane Number 96) or higher


But also read this from the hybrid owner's manual. This is the controversy and point of this thread. Is it necessary to buy expensive premium fuel just because the Lexus Owner's Manual mandates it for the hybrid. I am still not sure how to answer this when Lexus would tell you that it is required.

DocRock

I always fill with Premium. I like the results

Kulharin

I have a 2017 450H which is much better mileage than my 2010 450H.

Has anyone calculated the rough mileage improvements between regular and premium? I've been trying to test this based on my own driving... filling up with premium last time seemed to improve L consumption per 100km significantly over filling in up with regular the time prior.

jollick

As you know, the RX450h has a higher compression ratio than the RX350, here in the US the owners manual requires premium.

Millarduck

I think when all is said and done for this generation of RX, the 350 is the better value for cost of ownership. In my ownership experience, the mileage advantage of the 450h does not offset the cost of the required premium fuel it takes. If there is a 4 MPG spread between the 450h you gain range, but with a $0.75 spread between 87 and 91/93 octane it costs more to run the 450h. My assumptions:

Assuming 15 gallon fill-up:
At 23MPG 350 @$3.45/gal = 345 miles/tank costing $51.75. At 27MPG 450h@ $4.20/gal = 405 miles/tank costing $63.00, or $11.25 more. At the respective MPG I save 2.22 gallons (60 miles gained divided by 27MPG) with the 450h but it cost me $1.93 more than the 350 after I account for those gallons. (2.22 gallons better x $4.20/gal = $9.32 saved, but I paid $11.25 more than regular so it cost me $1.93 more for the 450h gas).

(I have never got above 29MPG on our 450h, and we actually average 26 MPG mixed. Our Jeep Grand Cherokee 4xe (PHEV) gets 24 MPG as just a hybrid on regular gas, so it costs less to operate gas-wise as a hybrid.)

This also does not account for longer term maintenance like spark plug changes or repairs like the water pump replacement which is more complex in the 450h.

jollick

@Millarduck It also depends on where you live and your driving habits. I do not do very much highway driving, mostly around town. I live in Georgia and get my Premium gas at Sam's Club, 93 octane currently paying $3.64 a gallon. I get 30 to 31 mpg. I am sure others will chime in on this topic.

GSFRX350

You guys pay far more for Premium compared to Australia. Yours is around 21% dearer compared to Regular, our Premium is around 8% dearer.
And in Australia the RX350 Gen 4 requires Premium so the 450h is definitely better value fuel wise.