Hi:

It's very hot in Florida. My car reads over 100 degrees almost everyday. My mileage is down almost 15%. Could it be because of the heat?

Glenn

 

Hot = AC

AC = Energy used
Energy used = fuel burned

Also batteries don't charge well when hot.

 

Unlike a pure EV where the battery pack is underneath the vehicle, and subject to the ambient outside temperature, the 450h traction battery is inside the vehicle (underneath the rear seats). Hence, the efficiency of that battery is a function of the temperature inside the cabin. Once the inside cabin reaches a moderate temperature, the traction battery should achieve optimal efficiency. A pure EV's battery pack will not achieve that efficiency in very low or very high temperatures as the battery pack must be continually heated in cold weather and continually cooled in hot weather. That continuous heating or cooling substantially reduces a pure EV's range.

Very cold or very hot outside temperatures do degrade the efficiency of internal combustion engines. So, I would suspect some of the reduction in fuel economy experienced in hot weather is due to the ICE. For example, the electric-operated radiator cooling fan works much harder in very hot weather.

As an experiment, a couple weeks ago I took an approximately 15 mile R/T (on essentially level ground on city streets) in the early afternoon on a very hot day. My 450h was parked outside and the cabin was quite warm when I started the vehicle. It did not take long for the ICE to reach normal operating temperature. The indicated MPG for the first five miles was not great. However, after the interior cabin cooled to a pleasant 72 degrees, the indicated MPG began to rise dramatically. When I got home, I parked the car in our garage which was more than 15 degrees cooler than the outside temperature..

An hour later, I repeated the same trip. The outside temperature was about the same as the first trip. The indicated MPG for the second trip was much higher than for the first trip.

 

I am in the market for a 2020-2022 RX. Trying to decide between 350 and 450H. In the Hybrid section of the forum, people say they commonly get 25mpg which equates to 9.8 L / 100KM (Canada). I assume that figure is average, not conservatie driving style which is more than likely what applies to me. I see people on this thread saying they get around the same? Is there a difference between the Hybrid in fuel economy or not? Also worth mentioning, I am in Ontario Canada and it get pretty cold here for at least 25% of the year.

 

keep in mind that 450h calls for premium fuel and 350 needs regular gas.

I’m averaging 11-12 L/100km on 2016 RX350 which is the same until 2022

 

The fuel mileage difference isn’t as dramatic as we would think/expect. I believe that’s because Lexus designed them with the intent of having similar power levels, although with a different transmission and a very different power band. Having said that, I have never recorded mileage that low, even in the coldest months of the winter. My lowest was 28 and my highest has been just over 36. Both of these numbers are exceptions however and my more typical mileage is 30-32. As another poster noted, premium fuel is recommended, however many people use regular grade with no reported issues. I would encourage you to drive both and decide from there. They have a different acceleration feel and given your stated propensity for spirited driving you may prefer the RX 350.

Edit: for what it’s worth, I do use premium fuel in the 450. Simply my choice to follow the manufacturer’s recommendation.

 

First are you comparing apples to apples?

If you are going by a realworld 25mpg for the 450h, then what 350 stat are you comparing to? It shouldn't be the EPA 27hwy. It should be also the real world 19-20mpg. So that's still a big 25% difference in fuel savings (not to mention an extension in max range).

Next the hybrid mpg is going to vary based on your driving habits and not solely just the driving style.
The hybrid will often achieve the EPA ratings and it's easier to meet them. Beyond the usual lead foot stuff, since city vs hwy mpg is about the same, you are shielded from the poor city mpg, I don't think that is not really where the mpg discrepancy comes from.

Where I found a hidden part of mpg will be greatly affected is initial startup as it will run the engine to attempt to quickly get it up to temp and ready to go for emissions purposes, even if battery is available.
So if you are a short tripper, you will get worse mileage than advertised... e.g
​​​​ drive 10miles, off for several hours, 10miles on, several hours off. If you did this for 200miles you'd get much worse mpg compared to if you did the exact same route with 15min stops
​​​. Maybe warmups are a big factor in canada that gets you to that 25mpg on the 450h.
That being said, you'll also see a mpg hit the 350 side as well with this driving pattern will probably drop the 350's mpg wrll below 20. This driving pattern actually is best suited for a phev or ev where you can be all electric

However, if you aren't driving that much, the short trip mpg doesn't matter in your tco, your long drives will hopefully make the majority of your miles.

The rest of the Canada lower mpg you cited I cannot explain, you can look on fuellly to get a better survey of real world mpg from mostly US users is around 28-29mpg for the 450h and 19-20 for the 350.
The only other idea I have for a factor in canada other than warmup probably is winter/ 3pmsf tires or rolling resistance/roads taking some mpg, but this would also something that hits the 350.

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Thank you and those above for your insights! There seems to be a 5k-7kCAD difference these days on the hybrid models (probably due to highly increased demand). Not sure if those costs will be fully recovered overtime but I do believe the ultra smooth transmission, and less wear and tear on parts will help negate the cost difference.

 

I did an analysis a long long time ago, check it out:
https://www.clublexus.com/forums/hyb...ml#post9049237
https://www.clublexus.com/forums/hyb...rt-2-cost.html
So far with the hesitation issues the 350 has been experiencing, I am glad I went with the 450h. Although I passed it to my parents and am now driving a different beast.

 

2022 RX450h here. My mileage has slowly been going up, 7.7L/100k now. Checked some conversion calculators and it says 30.5mpg and 36.7 if imperial is used. Been really happy with it so far.

 

2020 RX450h fill up at 13,543 miles 09/22/23. Traveled 435.0 miles, 100% city short trips mostly 14 miles each way, weather mostly 75F to 85F.
32.8 mpg calculated. The RX said 31.5 mpg. Filled up with Sam's Club Premium 93 Octane

 

Weekend getaway. 451 miles R/T. 11.847 gallons of 93 Octane. 38.07 MPG. About 95% highway. Average speed was lower than expected due to heavy traffic: stop-and-go several places coming back home. Weather was perfect with temps in the low 50s to low 60s with next-to-no wind.

 

That is beyond unbelievable. The best I ever got under normal conditions was 28 MPG. Jealous.

 

We used to drive 2015 RX350 AWD for approximately 3 years. Our mileage, driving approximately 40/60 highway/town, was consistently 19-19.5mpg overall per tank of gas. Exceptions were all-highway trips where we got up to 25mpg overall or all-town trips where it went down to approximately 17-18mpg overall.
Fast forward to now, we've been driving 2022 RX450h for just about one year. Bought it brand new, and first 3-4 tanks we had approximately 26-26.5mpg in mixed driving. Now it's average of 28-28.5mpg again in mixed driving. We use premium fuel only, never filled it up with regular. On all-highway trips we get 26.5-27.5mph, haven't done all-town trips yet, but I noticed that it's sweetest spot is driving on FM roads at around 40-55mph with minimum amount of stops. I mostly drive in normal mode, except in residential areas where speed limit is 25-30mph with frequent stop signs and lights, then I switch to Eco mode. I use Sport mode exclusively on highways when passing or when hard merge is required. While we haven't hit 30mpg (average tank that is, we've seen plenty of 30+mpg but overall per tank it's never gotten above 28.7mpg yet), we are aware that it is an older hybrid system and it's mated with the NA 3.5L V6 which is one of the biggest reasons we decided to get this RX before the switch to turbo-4s. Overall we're very happy with it so far and we plan to keep it for a long time if it proves to be reliable.

 

You’re in the right place.