Miles Per Gallon

[jeffro413]

hello all, i'm new here and a proud owner of an rx400h. my question is for you owners. what type of mileage should i be getting with my rx? it seems that - under "real" driving condations - i can only (not that its bad!) average 22mpg. am i doing something wrong? should be driving in a differant gear (such as "B" which i still don't know what it does)? i'm a rookie, and didn't get a very good explination. i just knew i wanted a hybrid and i love how the rx's look. its an 06 with 33K on it.

thanks in advance!

[ilovelexus2007]

hello all, i'm new here and a proud owner of an rx400h. my question is for you owners. what type of mileage should i be getting with my rx? it seems that - under "real" driving condations - i can only (not that its bad!) average 22mpg. am i doing something wrong? should be driving in a differant gear (such as "B" which i still don't know what it does)? i'm a rookie, and didn't get a very good explination. i just knew i wanted a hybrid and i love how the rx's look. its an 06 with 33K on it.

thanks in advance!

I see that you're living in Iowa, the cold weather will kill your MPG no matter what you drive. I'm currently get around 21-23 MPG for my 08's RX400h in this FRIGID cold weather in MN too. The MPG will improved significantly when Spring and Summer comes. I usually get around 26.5 to 30MPG in the summer, average around 28MPG. Congrats on your new RXh. Mind of I ask you how much you getting that for? Was it CPO? Premium Pkg with NAV I suppose?

[RX400h]

I have the same year and about the same number of miles. We consistantly average 24-25, but that includes my heavy foot on the weekends. Use the momentum of all that 4600 lbs to coast your way to stop lights, stop signs, etc. It really makes a difference when the engine is shut down for as long as possible. I almost always have the power schematic up on the screen so I can use electric-only mode as much as possible. This alone is a very valuable tool. It also really comes in handy when you're teaching a teen how to drive. I can always tell when the gas pedal is being depressed.

[Better Luck]

"B" is used when you are going down a long hill and you can use the engine to brake you to go slower. My mileage is around 23 in combined highway and suburban driving. I think of traffic in NYC when I think of city driving, stop and go and creeping or crawling in conditions that allow for electric operation only. If you are like me and live in the suburbs you are driving at thirty MPH or faster and unless you want to get dirty looks and lots of fingers you have to drive using the ICE to get the proper speed.

[Jim Clark]

We're averaging 27+. It's the wife's car and she has a light foot.

[jeffro413]

hello all, i'm new here and a proud owner of an rx400h. my question is for you owners. what type of mileage should i be getting with my rx? it seems that - under "real" driving condations - i can only (not that its bad!) average 22mpg. am i doing something wrong? should be driving in a differant gear (such as "B" which i still don't know what it does)? i'm a rookie, and didn't get a very good explination. i just knew i wanted a hybrid and i love how the rx's look. its an 06 with 33K on it.

thanks in advance!

I see that you're living in Iowa, the cold weather will kill your MPG no matter what you drive. I'm currently get around 21-23 MPG for my 08's RX400h in this FRIGID cold weather in MN too. The MPG will improved significantly when Spring and Summer comes. I usually get around 26.5 to 30MPG in the summer, average around 28MPG. Congrats on your new RXh. Mind of I ask you how much you getting that for? Was it CPO? Premium Pkg with NAV I suppose?

it wasn't CPO. i think i got a really good buy on it. so i could get it certified and it still would be a good buy. its my wifes car and we love it! thanks for the info, can't wait to see what it does this spring

[jeffro413]

I have the same year and about the same number of miles. We consistantly average 24-25, but that includes my heavy foot on the weekends. Use the momentum of all that 4600 lbs to coast your way to stop lights, stop signs, etc. It really makes a difference when the engine is shut down for as long as possible. I almost always have the power schematic up on the screen so I can use electric-only mode as much as possible. This alone is a very valuable tool. It also really comes in handy when you're teaching a teen how to drive. I can always tell when the gas pedal is being depressed.

how do you make it "electric only" i've got the screen up and only when i'm coasting and stopped that it goes that way. it just seems like i'm always using the engine. until at a constant speed, then it jumps around.

thanks for your reply

[RX400h]

While driving on a level road, briefly let off the gas pedal and then slowly depress it only to maintain your speed. You can sometimes be cruising in electric-only mode at 50-60 MPH. Driving around in a large store's parking lot should always be in electric-only mode. Just keep an eye out for startled pedestrians!

Dave

[artycuy7676]

Hey everyone! I too am new here and the proud owner of a CPO'd '06 RX400h (silver metallic). I picked mine up with 32K miles and navigation.

I agree that the "Energy Monitor" screen is an extremely valuable tool. It has really made me conscious of the way I drive. I've only filled up the tank once since I bought it and averaged 24.56MPG on the original tank. I'm currently averaging 27.4MPG after 173 miles.

I'm out here in Los Angeles so our traffic riddled freeways make for the best use of the electric motor. I actually find myself wanting to drive on the freeway in traffic vs surface roads... something's not right there. :)

[jrober]

I live in WI and I averaged over 30 mpg most of the time last summer (75% city driving commuting to work, 25% highway). With the cold weather we have been having (32 below this morning - ouch), I am down to 23-24 mpg the last few weeks. Don't worry to much about the mileage this time of year in Iowa. It will get better in a couple months. My last vehicle was a Chevy Blazer and I would have been getting about 15 mpg at best in this weather so I am still satisfied.

[tommygunn]

Here in Michigan; our 2008 is averaging about 24.4mpg (according to the Lexus computer). That has decreased from 25mpg during the summer/fall. I agree it is due to the cold weather.

[sdrose]

I have a 2006 model RX200h which I love. I've found that it gets the best mileage when I use the middle grade of gasoline. One thing I find puzzling is that when I fill up and do a manual calculation of the mpg, I consistently come out with a number about 2mpg less than what the car says I'm getting. I know it's not a huge thing, but I do find it mildly annoying.

Is anyone else seeing this? What grade of gasoline does everyone else use?

Julia

San Diego

[vinovelo]

I have a 2006 model RX200h which I love. I've found that it gets the best mileage when I use the middle grade of gasoline. One thing I find puzzling is that when I fill up and do a manual calculation of the mpg, I consistently come out with a number about 2mpg less than what the car says I'm getting. I know it's not a huge thing, but I do find it mildly annoying.

Is anyone else seeing this? What grade of gasoline does everyone else use?

Julia

San Diego

I too find (as most people seem to) that the computer is a bit optimistic.

Manual computatins can be misleading as well as I find that the tank will stop

filling with most nozzle switches 1.5 to 2 gallons of being full. So unless you

are filling it to exactly the same level manual computations can vary as well.

You would have to average several tank fillups.

As far as the mention of coasting in electric mode I find it varying and

sometimes frustrating. On level roads I can get it in electric mode at

about 35 mph. If I pulse to 40 and then glide down to 35.

All it takes is a slight bit of uneven pavement that is not level for a

few feet and the ICE kicks in. Then I have to pulse to 40 and back down

to 35. It's like a game.

Sometimes even at 20 with the engine hot and a near full battery level

the ICE seems to engage way too easy.

If I am VERY careful I can get 27 - 28.5 MPG in fair (60-70 degree)

weather. If I dont't drive with an extremely light foot it will drop to

24 - 26 easily. If I have fun with it....22.

This is with 70% or so highway and 25% traffic jams or city traffic.

Where it excels is long trips with rolling slow traffic with few stops.

Such as a bogged down highway for miles. In this situation I once

(only once) got 33 mpg on an 85 mile trip.

/Steve

[RX400h]

I have a 2006 model RX200h which I love. I've found that it gets the best mileage when I use the middle grade of gasoline. One thing I find puzzling is that when I fill up and do a manual calculation of the mpg, I consistently come out with a number about 2mpg less than what the car says I'm getting. I know it's not a huge thing, but I do find it mildly annoying.

Is anyone else seeing this? What grade of gasoline does everyone else use?

Julia

San Diego

For the most part, I use midgrade, although during the colder Winter days (55-65 degrees F), I can get away with using regular gas. If I travel to a very hot-climate area, like Las Vegas in the Summer, premium fuel is a must.

[ilovelexus2007]

For the most part, I use midgrade, although during the colder Winter days (55-65 degrees F), I can get away with using regular gas. If I travel to a very hot-climate area, like Las Vegas in the Summer, premium fuel is a must.

RX400h, so you are saying colder temp helps reduce engine knocking, therefore, premium may not required? I'm currently still using premium, and I'm in MN, so it's super cold with temp around 15-25F this week. I can definitely use mid-grade as some gas stations here priced mid-grade and regular the same. I don't care much about the $.20 different between premium and regular, but if I can save additional pennies, why not? Can you tell me where you get this info from?

[katzjamr]

the 400h will give better mpg with premium although it can run on a lower grade of fuel.

[sdrose]

When I first got the car 14 months ago, I used regular gas. I was very disappointed at the low 20's mpg I was getting. Then I read, think it was here in one forum or another, that some people were getting better mileage with higher grades.

I drive most of the time with the display showing current mpg. My driving habits have changed drastically. Used to be I only did the speed limit if a cop was behind me or when I was passing the speed limit by on my way to something just short of unsafe, charging up hills, that kind of thing. After watching the effect of such behavior on the actual mpg, dropping down to the single digits, that's a thing of the past. My kids say I now drive like an old lady. Whenever my 16yo daughter wants to use my car, she does so knowing she has to protect my mpg.

[RX400h]

For the most part, I use midgrade, although during the colder Winter days (55-65 degrees F), I can get away with using regular gas. If I travel to a very hot-climate area, like Las Vegas in the Summer, premium fuel is a must.

RX400h, so you are saying colder temp helps reduce engine knocking, therefore, premium may not required? I'm currently still using premium, and I'm in MN, so it's super cold with temp around 15-25F this week. I can definitely use mid-grade as some gas stations here priced mid-grade and regular the same. I don't care much about the $.20 different between premium and regular, but if I can save additional pennies, why not? Can you tell me where you get this info from?

It's a bit more complicated than this, but here goes:

Colder air is more dense in that more air molecules can be "ingested" by the engine for every "pull" of each cylinder. This is why many high-performance vehicles, including the RX400h have CAIs (Cold Air Intakes) to pull in air from outside the engine bay. As ambient temperature rises, so does the intake air temperature, though not nearly as much as does the air in the engine bay. Most vehicles also have knock sensors so that if intake air temperature rises enough so that predetonation of fuel occurs, the engine control unit will !Removed! timing (among other things). Of course, retarding the ignition timing results in a loss of power.

Hot intake air and regular fuel will result in predetonation and ultimately, a loss of power, but if the ambient temps are way down - as is the case in your area, running even regular gas should not result in any loss of power or fuel mileage. Things like using the seat heaters and the slight increase of rotating part friction will tend to decrease fuel mileage, but the bottom line is that you definitely do not need to use premium fuel when ambient temps are low.

Here's a real-world experience: Back when we had a Nissan Quest van, we'd use the manufacturer's recommended grade of gas - regular, and the engine ran perfectly well here in San Diego. However, once we drove the van to Las Vegas during Summer when ambient temps were over 100F, the engine would ping and stutter, horribly. After premium fuel was used, normal performance resumed.

Dave

[jrober]

"the 400h will give better mpg with premium"

Katzjamr. You keep telling us this so you must be an expert. Please show us your proof.

[katzjamr]

jrober: when i joined this group in june of 2005 the use of premium or regular fuel was a hot topic with literally hundreds of posts on this issue. at that time the owners manual didnt specify an octane grade. some people felt the 400h being sold as a green suv, should run on regular. some people wouldnt put anything but premium in thier lexus. many of us tried both and for those who did we found out:

premium gave a better throttle response, better miles per gallon (in most cases negating the higher cost) and a sharper jolt as the engine cut in and out during its normal operation, dont ask me why. regular was just fine for alot of people, they didnt want to spend the extra money, were happy with the performance, and the small side benefit of the smoother engine start and stop as it cut in and out most noticably at idle. (not at speed)

it takes three tanks on average to feel the difference one way or the other, going from premium to regular and vice versa.

as everyone knows i have never represented myself as an 'expert' on this forum. what i am is a person who has been greatly helped by the people who post here, and one who has posted hundreds of my own real world experiences in an effort to help others, not to mention a three and a half year 400h owner with over 45,000 miles on the odometer. i encourage you to do a search on this forum using words like, premium/regular/fuel/which/best, and see what pops up. that and a decent memory are my 'proof'. please feel free to use whatever fuel u want, variety makes the world go round.

[jrober]

In other words, your proof that premium fuel gets better mileage is that other people on this forum have said it is so.

I have spent considerable time researching this topic. It is clearly a myth. There is no more energy in premium fuel than in regular fuel. You will not get better mileage by using premium fuel. There are other advantages but fuel economy isn't one of them.

Here are a few articles.

http://www.mainarticles.com/Article/Is-Hig...-per-Year-/7267

http://www.torquecars.com/articles/fuel-octane-ratings.php

http://www.associatedcontent.com/article/3...on_premium.html

I can give you about 200 more articles if you would like.

You are correct that we can all choose which fuel we use. There is no sense though in posting false information like you have been doing about premium fuel and gas mileage.

I would happy to review some of your resources that prove the opposite.

As an aside, our own personal experiences mean almost nothing since there are too many variables, but I averaged over 30 mpg all last summer on regular gasoline (down to about 26 mpg this winter in Wisconsin). There was no difference in premium fuel the 2 times I tested it for myself. Again this means nothing compared to scientific evidence.

[skyfish400h]

I have spent considerable time researching this topic. It is clearly a myth.

http://www.torquecars.com/articles/fuel-octane-ratings.php

I don't mean to be picky, but the one of the articles you cited clearly says that lower octane ratings can lead to knocking which will cause the engine management system to take measures resulting in a loss of fuel economy.

So there is a link between octane and fuel economy. You can quibble about the chemsitry but the mechanism is clearly there.

[mindmachine]

In other words, your proof that premium fuel gets better mileage is that other people on this forum have said it is so.

I have spent considerable time researching this topic. It is clearly a myth. There is no more energy in premium fuel than in regular fuel. You will not get better mileage by using premium fuel. There are other advantages but fuel economy isn't one of them.

Here are a few articles.

http://www.mainarticles.com/Article/Is-Hig...-per-Year-/7267

http://www.torquecars.com/articles/fuel-octane-ratings.php

http://www.associatedcontent.com/article/3...on_premium.html

I can give you about 200 more articles if you would like.

You are correct that we can all choose which fuel we use. There is no sense though in posting false information like you have been doing about premium fuel and gas mileage.

I would happy to review some of your resources that prove the opposite.

As an aside, our own personal experiences mean almost nothing since there are too many variables, but I averaged over 30 mpg all last summer on regular gasoline (down to about 26 mpg this winter in Wisconsin). There was no difference in premium fuel the 2 times I tested it for myself. Again this means nothing compared to scientific evidence.

You are very wrong in your statement about fuel economy. I do however agree that premium does not have any more energy per gallon, but it is burnt more effeciently if the engine is designed for premium fuel. The Lexus engine is designed for premium and in the 2008 manual at least it even calls for premium. The problem in using regular is the anti knock system automatically adjust the timing to compensate for lower octane fuel and this in turn requires the enging to operat at less than optium design conditions and hence the loss of effeciency and this in turn lowers the fuel economy/MPG.

If the engine were designed for regular, ie lower compression ratio, them the loss of effeciency would not occour since the timing would not have to be retarded to avoid premature combustion/detonation. In this case, the use of premium would not increase fuel economy nor would it improve performance either.

I have written responses to this issue many times, it amazes me that people cant grasp the fact that the issue rests in the design of the combustion chamber and compression ratio and not in any energy difference in the fuel itself.

I worked for a company in their I C engine research and development, I am a retired engineer and I can tell you without a doubt that an engine operating at less than the optimal design setting in order to avoide premature combustion (detnotation) is operating at less than optimal effeciency (ie lower MPG). So when the engine is designed for premium fuel the anti knock additives in premium allow the timing to run at the optim design setting/effeciency and the maxium energy that can be extracted from the fuel will be.

One of my jobs while in IC Engine R & D was to facillitate combustion component related design changes in order to improve effeciency. We changed many design features like valves, and cylinder head configurations in order to alter gas flow and flame front flow patterns that would allow more effecient timing and hence improve effeciency. The engines I worked on were dual fuel and even tri fuel units, stationary power engines with much more horsepower than your Lexus, but the same engineering principles apply. The point of peek effeciency is a design point in every engine and it depends on all aspects of its design being utilized in order to achieve the design goals of both power and effeciency, fuel being a key component.

[SOMEONE ELSE'S GOT MY NAME]

the 400h will give better mpg with premium although it can run on a lower grade of fuel.

If you install an EBH (engine block heater, though some may not have access to a 110v outlet) and block your grill, the sub zero temps will have less impact, especiall if you have only short trips. Short trips are the real enemy of hi mpg's ... right next to extra cold temps. Battery chemestry isn't at a place, where efficiency remains high, below freezing.

[vinovelo]

Premium in of itself will NOT give you more MPG. However under certain conditions the engine computer will pull back the timing with lower grade fuels to prevent pre-ignition (pinging) which lowers the MPG. This is more noticeable in hot dry weather.