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Hybrid Vehicles Lexus RX 400h Lexus RX 400h - MPG-Real World Numbers
311 messages, Last post on Jul 08, 2009 at 3:52 PM
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Replying to: richcbt (Aug 18, 2007 12:07 am) 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.
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Replying to: chadx (Sep 24, 2007 11:24 am) Can you help with my confusion here? |
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| 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. | |
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.
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Replying to: kyxydj (Oct 04, 2007 1:18 pm) |
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Replying to: kaperino (Oct 04, 2007 3:40 pm)
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Replying to: gog8rsz (Oct 26, 2007 12:50 pm) 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. |
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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. 
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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). 
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Replying to: dorenescar (Jan 19, 2008 7:43 pm) |
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