Hello all,
New here and really hope this ends up in the right place. First hybrid, 2015 RX 450H with 57K, bought it CPO so everything should be good on it. I do a lot of hwy driving and I’m not sure if using cruise control is the right way to go with this vehicle seeing as I’m barely getting 24 mpgs my first couple tanks? It’s maybe a mile to get on and off the hwy home/work and I’m able to put the cruise on at 75 mph, that’s barely cruising speed here in Phoenix. I try to always keep it in the blue zone while driving, any help or suggestions would be greatly appreciated.
Thanx.
Kevin

 

I recommend turning off radar cruise as it will speed up and slow down too often otherwise. You can do this by pressing the button to enable cruise control, then push the stalk away from you for a couple of seconds.

 

Thank you for the reply, just have the regular cruise control on this one though...

 

At that speed, your fuel economy is not terrible. Hybrids really do much better in city, that is where their advantage over conventional cars really shines. The hybrid system is almost inconsequential cruising at fast highway speeds. In this configuration, the main electric drive motor actually switches to a generator function and the secondary motor normally thought as the main generator will add a little power into the system instead. They swap roles as most of the power is just engine to wheels, like a regular gas powered vehicle. At this point, most of your economy will come from condition of tires and how flat or hilly the terrain is. Cruise control will be great for flat terrain, but maintaining speed uphill will bring your economy down significantly. Fuel without ethanol will help too.

 

If I am not mistaken your question is more about MPG than cruise.
450-H shines in city (stop and go) traffic and on highway speeds the difference with 350 is not much.

The RX {most SUV) provide a larger resistance to air when moving. This drag is not linear and as the speed increases it increases exponentially (other wise the vehicles would keep on increasing speed as you let more gas in).

I would suggest look at the MPG threads to see how you can improve your milage.

Salim

 

I do a lot of hwy as well and I’m right around 27/28 mpg in my total average.

Now that I think about it though I am in the city somewhat often so maybe that’s skewing my average higher than yours.

 

Thank you again for the input/advice. It’s a pretty flat commute so it doesn’t really have to power up any hills? If using cruise isn’t an issue (didn’t think it was but being my first hybrid thought I’d ask to be sure) then I’ll go check the MPG threads and see if I can find anything in there that will at least get a few mpg’s closer to the 29 hwy they claim...

 

Try driving at 55, 60, 65, 70 and you will see the difference.

Salim

 

I get what you’re saying, but clearly you’ve never been to Phoenix out of snowbird season, those are side street speeds here... 😏

 

congrats on your new car. I love my 2010 RxH. You should reset all the history and start fresh if you haven't already done so. On easy freeway driving here in LA I get about 27 to 28 mpgs. Your mpg for a flat ride seems low.

 

Speeds above 55mph will bring your mpg down to conventional ICE vehicle level. That's it. You should have bought a fuel sipping diesel for such commutes.

 

I also thought forcing a brick through the air at 75 mph would result in terrible gas mileage.
SO
I put my cruise on at 75 and looked at the bar graph display for this speed and it was around sub 30 mpg or roughly 28 mpg, It was no where near 24!
This is what it took to move the brick down the road so it should also reflect a long distance commute at this speed.

I think these cars learn a driving style and for some reason they don't update it.

I'm probably going to catch flack for this but I recommend you disconnect the battery and start fresh. I did this as my battery was low and have been getting 29-30 mpg without trying all- sub 45 mph but before this disconnect I had changed my job thus my driving and was suffering a loss of ~2mpg. (27 down to 25) I am now getting my absolute best mpg without very slow acceleration and without anticipating braking to any great deal.
Just look up how to do it correctly or take it into the dealer.

 

Are you using premium fuel? The 450's are rated using premium and get fewer MPG's on regular.

 

premium fuel is not required on these cars. I have a 2010 RXh and I only use 87 octane. I experimented a lot with 87, 89 and 91 and the gain was negligible.

 

High octane is a high HP requirement and not a mileage requirement. By not using the required octane the engine has to detune itself possibly resulting in a change in mileage. This is a loss of power and is also assuming the engines system can do this under any load so that engine demons don't come a "knockin"
High octane fuel burns slower allowing an engine to produce more HP, if it was built for it, which this is.
To run on a lower octane fuel requires either the engine be detuned or ruined. Even if its detuned this may not be enough. Hot weather and a loaded engine can knock.

Your Rx 450h does indeed Require 91 octane fuel. As it is stated in your owners manual.
If Lexus could have built this engine and given you the choice in octane, believe me they would have.