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Lexus RX 400h - MPG-Real World Numbers

357 messages,  Last post on Jan 04, 2013 at 8:01 PM

You are in the Lexus RX 400h Forum.

What is this discussion about? Lexus RX 400h, Fuel Efficiency (MPG), SUV

Messages Page 35 of 37

#335 of 357 Poor city milage by rx400hawd

Dec 13, 2010 (11:04 am)

I'm new to this forum today and have not reviewed all the posts, but you guys seem to have the potential of being more helpful than my dealer's service department...
I bought a certified RX 400h (2006) with 45k miles in Sept. 09. I love the car but the milage in-city has been very disappointing. I'm getting ~18-19 mpg in the city and ~24 on the Highway.
I was under the impression that a Hybrid would give better mileage in-City than on the Highway.
The service adviser at the dealer first told me the low mileage was because of using regular-octane gas. The next service I had another adviser who said that should have no influence on the mileage, and the service chief felt it may be related to the wider all-season tires (which the car came with from the same dealer).
My take is that when I spent the extra funds to get a hybrid, I would expect better in-city mileage than that. I have noticed that it does not take much for the engine to start up, when starting to drive. Often when I start the car the engine starts too (even if the battery indicator is near full). When braking I often note the gauge (on the left) not to dip into the blue zone, but it sometimes does - and I have not been able to find any related factors or any consistency.
So my question is - is this kind of mileage to be expected, or should I go back to the dealer and demand that they figure out what's the problem is?

#336 of 357 Re: Poor city milage [rx400hawd] by ronjo

Dec 13, 2010 (11:26 am)

Replying to: rx400hawd (Dec 13, 2010 11:04 am)
I too have the RX400h(2006) model with the same 18-19city/24highway and I drive like a granny. My tires are the high pressure gas saver tires (Michelin) and it did not help. Disappointed as well. Some systems on the car are not fully electrical so the car will start if you need them - e.g. heater comes from engine heat (it's not instantly hot)-so car must start.
Please take it to the dealer and find out why 'bad' mileage. My dealer seems to fix things but does not know the technology to advise why. I talked to the designer of the Hybrid at a Football game (USC), and he said Lexus hybrids are tuned for performance and not best gas mileage; Toyota tuned for mileage. Still too low for me - please take it in and let us know.

#337 of 357 Re: Poor city milage [rx400hawd] by bocastephen

Dec 13, 2010 (12:44 pm)

Replying to: rx400hawd (Dec 13, 2010 11:04 am)
Those mileage numbers for both of you are unacceptable for this car, especially for city.
 
Most dealers refuse to do the reset I described earlier - not sure why, but their usual approach to mileage issues on hybrids is to become very hostile and blame it on the customer or say Lexus hybrids are not designed for improved mileage.
 
So - since I'm continuing to avg an indicated 29-30mpg actual, 65% hwy and 35% city, I know it can be done.
 
Do the reset I described upthread and learn about pulse driving. Make sure your tires are inflated properly (to spec, not overdone). Make sure you're using national brand gas - but it doesn't need to be premium (although running a tank of premium through once in awhile doesn't hurt).

#338 of 357 Re: Poor city milage [bocastephen] by delegator

Mar 15, 2011 (10:46 am)

Replying to: bocastephen (Dec 13, 2010 12:44 pm)
First, responding to the post above that thought most RX330 owners get 13-14 mpg. I have an RX300 (model year 2001) and have consistently seen 18-19 MPG in winter and 19.5-21 mpg in the summer overall. My commute is about 16 miles, 2/3 highway, so it's a reasonable mix. That's in NH. So, I don't think it inconceivable that a conventional RX400 could get around 20 if there was a good amount of highway driving in the mix.
 
Regarding dealer responses to low mileage, I had a chuckle at somebody being told that it was because they used regular unleaded. I heard the same fairy tale from my dealer: "your mileage should improve by about 10% with premium". He further said that it might take 2-3 tanks before I saw the benefit because "the oxygen sensor would need to recalibrate itself."
 
Poppycock. I changed to premium (made sure to get the tank below 1/8 4 times in a row, filling with premium each time) and then started measuring. My mpg with premium unleaded actually dropped by a full 1+ mpg.
 
I don't have an answer as to why you are seeing so much lower than advertised mpg, but I'm sure the dealer has a whole bunch of reasons that don't involve him doing work.

#339 of 357 Re: Poor city milage [delegator] by mattmansmitty

Apr 08, 2011 (1:08 pm)

Replying to: delegator (Mar 15, 2011 10:46 am)
I read alot of these posts before I bought my 2006 RX 330 (used on Craigslist) in January. I had found an RX400h same year and was tempted but my wife wasnt ready to buy so I held off and it sold. He claimed he got around 28mpg on a regular basis.
 
So with the 2006 RX330 my wife gets 14mpg! Which sucks!
When I drove it on the highway the best I got was 22mpg!
We've had it for about 3 months now...
 
Side note:
I own a Prius and get an avg of about 40 in the winter and 50+ in the summer. City driving it does worse than highway, I commuted in and out of DC for 3 days for training and it dropped to 34mpg in March (it was colder out). As soon as I was on the highway it jumped back up to 43mpg.
So Hybrids do worse in the city than highway, highway you can coast and are using a combination of electric and gas power at times. Unless you mash on the pedal which then you can hear the gas engine kick in.
 
Also about premium fuel vs regular in any car, CarTalk had this to say:
http://www.cartalk.com/content/features/premium/questions.html
 
And according to the RX330's manual it states, "If premium fuel cannot be found near you, regular fuel may be used for short periods." Consumer Reports also lists the 04-06 model's fuel type as regular, although the gas cap on the car states Premium Only... Not sure about the 400h's fuel type but premium doesnt make a difference in mileage unless the car absolutely calls for it, and even then it might not make a difference.
 
At 14mpg honestly I'd be happy with 24-28mpg, especially when we're gonna see $5-6 a gallon gas.

#340 of 357 Re: Poor city milage [mattmansmitty] by skycaptain

Apr 08, 2011 (2:20 pm)

Replying to: mattmansmitty (Apr 08, 2011 1:08 pm)
mattman, I have a 2007 AWD RX 400h and I get a 28 mpg combined almost always except in the cold winter. In winter the engine runs more to warm up and I pretty much get a constant 26.5 mpg combined. The best city mileage I ever got was 33.8 on a 12 mile loop in 45 MPH stop and go.
 
          Luke

#341 of 357 Latest update -- no change!?! by sunilb

May 26, 2011 (9:17 pm)

So, the wife's 2006 RX400h AWD recently had the following done:
 
1- throttle body cleaned;
2- oil change;
3- new tires (Bridgestone Alenza); and
4- ISC reset done -- the tech did this without hooking the car up to the machine (revved the engine)
 
This was about 6 weeks ago and last week, we took our first extended road trip (SF->LA and back)... gas mileage has not changed... still in the 22-24mpg range. Note: I am going by the onboard display (not calculating it by hand)... I had reset the mpg counter at the start of our trip. Temperature was moderate (65-85 degrees) and there were some crosswinds and elevation changes.
I don't recall my average speed but driving on Hwy 5 generally means driving between 75-80mph to keep up with traffic.
 
Does anyone think that the ISC reset needs to be redone the other way? What else could be done to improve mileage (or is the very high mpg that some are getting due to living in flatter parts of the country?).
 
Lastly, whatever happened to Edmund's long-term test of the 2006 RX400h?
 
Appreciate any and all responses!

#342 of 357 Re: Latest update -- no change!?! [sunilb] by dmbflorida

May 27, 2011 (7:00 am)

Replying to: sunilb (May 26, 2011 9:17 pm)
I get better mpg on flat land but I have a FWD 2006 400h and you have an AWD so this could a reason for difference in fuel economy. I have driven I-5 and know the elevation changes and winds North of Los Angeles but my guess is that your mpg drop is partially due to the high speed you are driving.
Maybe you will get better mpg when you drive a highway where you are not required to drive 75-80 mpg My mpg, with A/C in hot SW Florida, averages about 26 -27 mpg. However, when a grandkid drives my car, the mpg drops to about 24 mpg so driving patterns make a difference too. good luck.

#343 of 357 Re: Sudden Change in Mileage [sunilb] by normrl

Oct 25, 2011 (1:24 pm)

Replying to: sunilb (Dec 05, 2010 9:49 pm)
I experienced a sudden change in mileage from a constant 26.4 mpg to 30.2 mpg this summer. We had an "inverter pump" failure on I20 near Abilene, TX and had to be carried to FW for repair. When the new inverter pump arrived and was installed, we were back on our way to NM. Not for long we broke down again. Ultimately, the computer was wrong it was the radiator which was plugged. On putting a new one in, we were again on our way and saw about a .1 mpg each half day.
 
We did decline once we left New Mexico's mountain this Sept. to 29.6 mpg. It sure seems to me that something in the repair is responsible, but the dealer says no.

Messages Page 35 of 37

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