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Lexus RX 400h - MPG-Real World Numbers

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  • sunilbsunilb Posts: 407
    edited May 2011
    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!
  • dmbfloridadmbflorida Posts: 38
    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.
  • normrlnormrl Posts: 1
    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.
  • I have a Lexus 400RX 2007 with 42K miles. I recently discovered I am only getting 20MPG in the city, and 25 Highway. Go figure. I went to Lexus dealer and ask them why I was getting this low gas mileage. They gave me some standard lexus answer like " It all depends on how you drive the car", and a whole bunch of other excuses. The service manager proceeded to tell me to set back the fuel gauge every time I fill up, that should help this situation. He set it himself, and I drove for 2 days, with still 20-21MPG. I am really steamed beyond steamed at this. I called Lexus corporate to explain the problem, and they advised me to take the car in to have the Hybrid system checked out and get back to them. Well, I took the car in and had a full diagnostic run on my car. My car came back with NOTHING wrong, as a matter of fact, they told me my car was in excellent condition. Well, we have got a problem here now. So I need to call them back. I paid 51K in 2007 for a hybrid that I thought was giving me the gas mileage it stated on my sticker . I still have my original sticker. If this is the case, I have spent way more for this darn car. Something is really fishy with this and I am going to get down to the bottom of this. Please if you are having the same problem, post it, call Lexus. They need to be held accountable. I am going to hold Lexus accountable.. I really wanted a Bentley, for what I think I have paid for this car if the gas mileage was not truthful, and as much as I love it, I could've gotten my Bentley. Who knows, after I finish with this, I may just get one.
  • ronjoronjo Posts: 4
    What does the original sticker state ?
    1) I have a 2006 RX-400h and get about the same mileage as you. My whole family says I drive like a grandma (slow), since I'm trying to get the maximum mileage.
    2) I met a Toyota engineer at a football game and complained. He said Lexus is tuned for performance (it is a fast car) and not mileage. The Toyotas get better mileage with same equipment. But..I'm like you - why does it say on the sticker?
    3) Disappointed. Trying to save gas, be green, encourage innovation (all with a price tag) and it falls flat.

    Please continue you inquiry and post what you find ! Thanks!
  • I posted to this forum awhile back to see what the difference was between the RX400 and the RX330 (which I have). When buying I did have the option to get a RX400 but opted against it since I already had a Prius and didnt want 2 hybrids just in case there were issues.

    So that being said the RX330 averages anywhere between 13mpg and at best 22mpg! I dont remember what the sticker said but 2006 was BEFORE the reevaluation of the mpg estimates put out by the Fed. Supposedly the old tests didnt account for city driving and different conditions which lower full economy. The old setup was way off on every car, since the revamp every single car's mpg was lowered, even my Prius which was supposed to get in the 50's but really gets in the 40's. Also account for different times of year, hybrids dont do well in the cold or the extreme heat due to battery efficiency. My Prius will get in the 50's in the summer and the low 40's in the winter, sometimes in the high 30's.

    So if you guys are getting 20-25mpg that's probably accurate compared to the non hybrid model. That and the hybrid adds a good 400lbs plus to the gross weight of the car.

    Just my 2 cents!
  • I just bought a Certified Pre-owned 2007 Lexus RX 400H, less than a month ago. I was on getting 20 MPG, which is completely not what I was told that I would be getting (28/26 city/highway) by my salesperson before I bought the car. I believed because it was certified by Lexus (a brand known for living up to quality) that I wouldn't have to be worry about get the correct MPG.
    After a couple weeks of delay, I finally got the Lexus dealership to service it to look at the MPG issue. The service folks just called and said NOTHING was wrong with it and unfortunately it depends on how you drive and warming up car/heat. I tried to ask them about an ISC reset and they said they heard nothing about that. I told them I purposely drove extremely cautiously, minimizing the use of gas and trying to coast as much as possible before I had the car serviced, but it did nothing to improve the mpg. Thus the service response to me was completely unacceptable and said the best they could do is have my salesperson call me tomorrow as he was the one to tell me repeatedly that it should get 26-28 mpg. It is unfortunate that the service people and sales people act like they work at 2 different companies. After the service person said they didn't know what MPG the car should get, I said surely Lexus should have that it print somewhere, which they conceded and then I said hypothetically that someone in the world should be able to drive the car and get the 26-28 mpg that I was told I would be getting. She finally agreed that "somebody" should be able to drive the car and get that kind of MPG.
    I made a conscious decision to buy the RX 400H vs another SUV which would be less expensive as I believed I would save on gas over the next 6-8 years that would reduce the cost difference. If a car is Certified by Lexus, it should live up to the Lexus brand standards, the poor MPG is not acceptable. George, my salesperson is a really stand-up guy and a man of his word, so hopefully when he gives me a call tomorrow he'll make things right by either fixing my car or replacing it. I am hopeful Lexus will do the right thing and make things right. I'll keep everyone updated, if Lexus or anybody else wants to try to help me resolve this issue, it would be appreciated.
  • mckbmckb Posts: 1
    Thank you for this good description. After just purchasing a 2006 RX400h, you can imagine my disappointment driving on a road trip and seeing the mpg peak at 23. Mostly 22, and no different around town prior to the trip. I had done what I thought was the correct procedure according to the tsb, but I did not first drain the batteries as you state to do here. That made all the difference. Found this thread while at the hotel, and tried it the next morning... that second day of the trip, the average jumped 20%+ to over 27 mpg! Now I thoroughly love this car! It doesn't seem to make sense why this works, and is an odd quirk to the vehicle, but it certainly does make a big difference.
  • cvav1615cvav1615 Posts: 3
    I own a 2006 AWD RX400h, and have been the sole owner and driver. I am more of a highway or country/windy road driver as opposed to a city driver. I have never felt that I got the full benefits of owning a hybrid, but never complained with the 25-28 avg MPG (my previous vehicle was a Ford Expedition, which averaged 10-12). I am not a 'gentle' driver, but not an Indy racer either. In the past 2 months, my car has gone from the 25-28 avg to 18-20 MPG. With the 15 gal tank, where I used to avg anywhere from 320-360 miles per tank, I am lucky to get 260-280. I have not changed the tires in this time frame, I use the same gas, from the same station majority of time, which has always been the premium blend. Tire pressure is fine, and tires have been rotated at 5000 mile intervals... Nothing has changed!! I am just puzzled on the significant change in fuel economy. Yes, it is winter here in SW PA, but the temps have been quite mild compared to previous winters, and my car is garage kept the bulk of the time. Anyone have any suggestions or opinions as to this change? Thanks!
  • Dear Cvav,
    I would try an ISC reset procedure to reset the battery charging logic. I have copied the procedure from an earlier post. Here it is...

    When you reset the ISC, you idle around and drain the battery until the engine comes on, then shut the car down. You turn off all accessories and climate control (nothing electronic should be on). Put the car in run mode (start it), press the brake pedal, put the car in drive, then while holding the brake pedal down, press the accelerator pedal down.

    The car will not move or rev much, but the engine will be on and start charging. Keep the gas pedal down for 40 seconds, then release it for a few moments, then down again for 40 seconds and keep doing that 40 on/10 off etc until the battery is fully charged (all green) and the engine no longer charges or revs slightly when you press the gas pedal down. Of course you're holding the brake pedal down all the time while doing this.

    Shut down, put your accessories back where you want them, then you can start up and go anytime. Learn about pulse driving to maximize your mileage going forward.

    :shades: Luke
  • cvav1615cvav1615 Posts: 3
    Thanks Luke, I will try this. Just one question, how will I know the battery is full, in the green, if I do not have the Nav screen on to show me the Hybrid system? Thanks!
  • avery1avery1 Posts: 372
    Maybe the oil company changed the gas composition to be less polluting. Ethanol will reduce mileage.
  • Cvav, You leave the screen on for this procedure so you see the Hybrid battery turn green....Good Luck!!....

    Luke :shades:
  • ahaberahaber Posts: 1
    I just purchased a 2008 RX 400 H . the millage is great in city 25 mpg.

    The problem with consumption is how you drive , when I am driving is 25mpg when my son driving is 19 MPG
  • Dear Luke: Merry Xmas! My Rxh 400 2006, died on me yesterday with two messages Check VSC and Hybrid system. Would the above procedue help me so that I can get it to the mechanic? I was supposed to take into the shop last week but scheduling got the best of me, the maintenance required light went on and with the holdiays couldn't get there. My car and I have been through alot and its been serviced regularly "old blue" has been through many a bad snow storm and icy roads and has been pretty good on the mileage too.

    Best,
    Alice And Happy New Year All!
  • About how long does it take to recharge the battery while doing the 40on/10off? Just bought a 2008 rx400h and the mileage is lousy and I've been really conservative in my driving.
  • clintonpclintonp Posts: 1
    If you live in a cold weather climate the gas companies change the make up of the gasoline to aid starting in cold weather. This gas reduces the mileage on most vehicles and especially on hybrids. September is the month when cold weather gas is introduced and ends in May. I had a Prius and I got 51 mpg I summer and it went down to 41 in winter.
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