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Lexus RX 400h - MPG-Real World Numbers



  • richcbtrichcbt Posts: 8
    To be honest, I stopped paying much attention to the mileage a few months back, but according to the computer on board I'm currently getting 23.7 mpg. I'm using 91 octane gas. This is for the last 4755 miles.

    I have never gotten much better than that.

    Most of my driving is in the city, on relatively short trips around town, especially during the summer when I'm not taking certain trips I normally take on the freeway.

    I believe my best sustained mileage was around 25.5. I guess you could say I'm not happy, at least with that aspect. I had an RX300 and I believe that car got close to 18-19 overall. It didn't have the power, but it rode better, was much better in terms of driver vision, and the Levinson sound system sounded better to my ears than the new one. Lexus didn't recommend premium fuel, either. I drove my RX400h for a while on regular and it runs fine, but to me it runs a little better on the 91 octane.

    But it's hard not to like the vehicle, overall. I must say, I don't have a fetish about getting extremely high mileage, and wouldn't drive differently just to get better mileage. If I need to accelerate, I do. But I don't have a leadfoot, and don't see why my mileage would be much different than anybody's. Out in traffic there are always situations in which stepping on it might help, as for instance at a light in order to get past a slower vehicle, and change lanes. If I need it to go, I do step on it. If I'm in a hurry, or want to make a light, or whatever, I do give it the gas.

    My guess is that I drive pretty much like most people, at least most who don't have a hybrid. I'm 55 and haven't gotten a ticket in about 15 years.
  • grallajgrallaj Posts: 1
    I just purchased a 2006 RX400h yesterday. It was a corporate car previously, had less than 20,000 mi, and got the certified used warranty extended to 5 yr/100,000 mi.

    I wanted a hybrid vehicle for some time, but I am a little concerned over getting the best mileage... Any tips?

    If the mileage is not working out well, can Lexus do anything? Like check the batteries, etc.? :confuse:

  • avery1avery1 Posts: 372
    Congratulations. Do you mind telling what you paid?
  • PF_FlyerPF_Flyer Pennsylvania Furnace, PAPosts: 5,854
    If you are a long-term hybrid owner, our Senior Editor, John O'Dell, would love to hear from you! A short email with your maintenance experiences and concerns would be great. Please send to John at by close of business Wednesday, August 22, 2007. Be sure and include your Forums username.

    Need help navigating? - or send a private message by clicking on my name.
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  • chadxchadx Posts: 153
    >>> I drove my RX400h for a while on regular and it runs fine, but to me it runs a little better on the 91 octane. >>>

    On these vehicles, as with non-hybrids rated for 87 octane, there is no mileage or performance benefits to running high octane gas. You simply pay $.20 extra with no benefit. The engine is designed with a low enough compression ratio for low octane. High octane gas resists self-detination at higher pressures, but unless your engine is designed to take advantage of this, there can be no benefit.

    Note that on modern vehicles where premium (high octane) is recommended, you can run low octane without damage to the engine. The vehicle will compensate for the low octane by tweaking the timing, ignition, etc. (Note: older vehicles do not account for this and detination, and engine damage, can occur). When running low octane in modern premium-recommended vehicles, an associated decrease in performance and mileage will occur. But for an engine desinged for low octane, no performance or mileage increase can be realized by running premium.

    On a related note, for an accurate 'operating cost' and mileage comparison, a person should consider the manufactures recommended octane when choosing a vehicle. For example, if a vehicle, where premium is recommended, gets 20mpg and another vehicle gets 20mpg with regular octane, and there is a $.20/gal price difference, over 20,000 miles, 1,000 gallons of gas is used. For that 1,000 gallons, a $.20/gal difference amounts to $200 extra for fuel costs from two vehicles that get the exact same mileage. (Your savings may vary if your area does not have a $.20/gal priced difference between Premium and regular).

    So, not only does the RX hybrid get much better mileage, but it does so on $.20/gal cheaper regular gas rather than using premium gas like the RX330 non-hybrid.
  • Unless I've misread your note, it seems that there's a contradiction, and I look forward to understanding it better. You seem to agree that where premium is recommended, a decrease in mileage will occur when you use regular gas. Then you say that "On these vehicles [the RX hybrid] there is no mileage benefit." Is it your understanding that the manufacturer does not recommend premium? My owner's manual as well as the website require premium fuel. The website (footnote 3) says: "Ratings achieved using the required premium unleaded gasoline with an octane rating of 91 or higher. If premium fuel is not used, performance will decrease."

    Can you help with my confusion here?
  • I've had the '07 RX 400h for 4 months and have 6200 on the odometer. The computer shows that I'm getting 25.6 in town and 26 on the road. This is in flat Florida. In the montains of NC the computer says I was averaging 29. I'm a conservative driver and strive for maximum MPG. To check the accuracy of the computer around town, I did a manual check on the MPG, dividing the miles travelled by the number of gallons to fill-up. My calculation revealed actual MPG of 22.3 against the computer average of 25.6. Has anyone else done a similar validation? I really enjoy the car, but would be very disappointed if the computer actually overstates the MPG.
  • kyxydjkyxydj Posts: 12
    I've found that the MPG computer in my 2006 RX 400h is fairly accurate, although I have a friend who says the one in his Prius is "optimistic." I find that a "manual check" of my miles per gallon can be an inexact science, depending on which pump, at which gas, station I am using. They all seem to shut off at different times when they think my gas tank is full. But when I've worked out the MPG "manually" I've found numbers higher and lower than what the Lexus computer says, so I'd say it's pretty good. BTW, I stopped resetting my MPG computer at each fill up; I now have driven almost 3000 miles since my last reset, and the average MPG is holding at 29.0.
  • Curious on the manual calculation. Do you include the two extra spare gallons in reserve when you caluclate?
  • In doing the calculation, I determined the number of gallons to fill-up. When the automatic pump cuts off, I can usually get in about 2 more gallons. It is a max fill,just before overflow.
  • sdk43sdk43 Posts: 4
    Our 400h is almost two and half years old.
    In the NY-CT area on 87 octane we average 26-27 mpg, and 28 mpg if we take hour-plus trips and stay below 70 mph. I tried one tank of 91 octane last spring and mileage seemed to be 1-2 mpg higher, but that doesn't do more than pay for the higher price so we use 87 octane.
    Speed makes a big difference--even if our mileage indicator has not been reset for over 200 miles, if we get up to 75 mph you can see the integrated mileage number drop in a matter of minutes.
  • Had the rx400h for 6 months and very pleased. I can get 30 mpg on the computer driving carefully with a mix of highway and city driving in warm weather here at 6000 feet elevation using premium fuel. My wife likes higher g forces and gets closer to 27. Anyone else have experience at altitude? An earlier post on this forum describes it as effective to accelerate quickly to speed and then take the foot off the accelerator quickly to engage the electric motor and that this strategy enhances fuel efficiency. Physics seems counterintuitive, but maybe that's the way the car's computer is programmed. I should think that it would be easy enough to "tune" the software for better performance or better fuel economy. I'm a little surprised that this is not possible for the driver to do as a matter of individual preference. Maybe next year. :)
  • We were worried that our 400h might never consistently do it, but after 6k it all of a sudden jumped to 29-30.5 mpg with mainly stop and go city driving. Interestingly, it was our first tank of mid octane; we had always used premium before. It definitely declined during cold and rainy weather, but that may be because we were driving differently. We love the car in all ways, except I can't wait until it becomes a 7 seater ('10, I believe). :shades:
  • I had the same experience. About the same mileage as you, my MPG in town went from 25 to average 28.8 and has stayed the same for the last 2600 miles. I live in Florida and use premium fuel in the '07 model I bought last summer.
  • Just picked up my 2008 RX 400h -- love it. Mileage will improve after a few thousand -- as happened with the Honda Insight, Honda Civic Hybrid, and Prius, I'm sure. But already getting 25-28 on various trips around suburbia and commuting into DC. I brought it in for a day for XM and hitch installation -- and had an RX 350 loaner -- and it had 19.5 mpg over 13,000 miles and I just got about that for the day, I think. Anyway that is some 25% bonus for hybrid.

    Will by trying regular fuel next tank. $.30 differential doesn't seem worth it if no engine damage from 87 octane. Manual says it will run on it. And even says to use 87 octane with ethonal blends. Can't claim to understand it all.

    Like the car. First car I've owned all tricked out like this.
  • I live at 7,000 feet and have had a 2007 Lexus 400h for 11 months.
    For the first nine months I averaged between 28 and 30 mpg on regular gas. For some reason, I've been averaging only 22 to 23 mpg
    for the last two months. Still buying gas at the same place and no change in driving habits. The dealer says nothing is wrong and refuses to do anything. Have you heard of any problems like this?
  • I have exactly the same problem you mentioned.

    I live at 7,000 feet and have had a 2007 Lexus 400h for 11 months.
    Current mileage is 9,500.

    For the first nine months I averaged between 28 and 30 mpg on regular gas. For some reason, I've been averaging only 22 to 23 mpg
    for the last two months. Still buying gas at the same place and no change in driving habits. It's impossible to drive even 4 mph without the engine turning on. But for the first 9 months I could drive 20 to 30 mph on electric power alone.

    The dealer says nothing is wrong and refuses to do anything. Have you heard of any problems like this?

    Incidentally, it is winter here and I thought perhaps using the heater would require the engine to stay on. So I turned off the heater for about 20 miles and started monitoring mpg from zero. I ended up with 22.4 mpg.
  • Hi,

    I'm guessing the Toyota firmware is the same in your RX400h as it is in my Prius.

    1) The heater does want to be ready to serve and hence the motor runs all the time during cold weather, particularly at stop lights and any acceleration at all.

    2) Ethanol blends here in Colorado during the winter months at 10% lower my mileage by *exactly* 10%. So that's 2.8mpg less for you plus the heater...

    Try taking a road trip to boost your mileage.. Seems to help over the city driving in the winter.

    Good Day, John
  • kyxydjkyxydj Posts: 12
    Yes, with the heater on, it makes your gas engine fire up immediately upon starting the RX 400h. And keeping the heater on for your trip will also keep the gas engine operating, when it might otherwise turn off. I've also noticed lower gas mileage on my 2006 RX 400h in the winter months, basically anytime it's under 65 degrees F. outside (I live in San Diego). If you live at 7,000 feet, your winter is probably much colder than here in San Diego, so you are going to see a bigger drop-off in mpg. The gas engine just seems to operate a lot more when it's cold outside. I am sure your mpg will go back up to previous levels once the outside temp. warms up!
  • brent99brent99 Posts: 19
    I get up to 20MPG driving city and 23.5 on long trips (AWD). Car is over 20,000 miles, this has been pretty consistent during my ownership.
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