Gas Mileage On Your Rx400h

[patt]

I've got a data point on longer trips versus short trips with the same drivers in hot weather.

We have been consistantly getting between 25 and 27 mpg during our normal driving - 15-20 mile commute trips plus a smattering of short 1-5 mile errands, AC as needed, about 70% suburban, 25 % freeway.

For about two weeks we had a family event going on for which we took time off - no commute, all short errands up to about 6 miles at most, a lot of drive a mile here, two miles there. I did try to daisy chain errands where possible, but there are still times where a stop is long enough that one starts again with a cold engine and a hot interior. The daily highs were in the 90's and 100's. For the two tanks we drove that way (an awful lot of short errands) we got between 22 and 24 mpg.

For reference, the Sacramento area is a typical water sculpted valley. A lot of rolling little ups and downs. The uphill costs some mileage but I get some of it back on the downhill.

If your usual driving is very short trips, don't expect to get EPA numbers (which are both done over 30 minutes or so and one of them with a warmed up engine). That is probably true of every car, but this car is the first where I've watched the mileage so closely.

It is a very nice car and we are very happy with it. Its mileage is a lot better than the small SUV rental I got for one week recently on a trip and it is a lot nicer.

[jj_fender]

First of all, short trips will kill your oil quickly, so avoid them like the plague. Secondly, it doesn't matter what vehicle you are driving (except pure-electrics) - short trips kill mileage. The beauty of full hybrids is that you can get stuck in daily traffic and actually gain mileage compared to just cruising at highway speeds.

As a general rule-of-thumb, make sure all trips are at least 8-10 miles long or are combined to achieve this distance.

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How in the world does anyone "make sure all trips are at least 8 - 10 miles long ..."

Am I supposed to pick a grocery store that is ten miles away just so my average will go up?

Does the posted 30/27 MPG only apply to people that live at least 10 miles from the nearest store? That doesn't make sense.

[Vegas 400h]

I got my 400h on May 1 and have over 4000 miles on it. I have the AC on all the time. The temp gets to 90s in May and around 110s in summer here.

Granted, I do drive differently than a regular car - slower starts (engines starts about 15 mph) and coasting when I can - I get 28 mpg average.

Vegas is a sloping valley with the West side sloping down toward the Vegas strip. I can get 34 mph going toward the strip but going back home i only get 25 mpg. The speeds here are mostly 45 mph in the suburbs and rarely 35 mph zones.

I think this car is fast for an SUV. I love the CVT. Acceraleration is so smooth, you don't even know you are at 80 mph.

One tip: check your tire pressure monthly. I actually increased my tire pressure to 35 (factory is 30 psi). Less rolling resistance without much difference in handling. Maybe this is the reason for my high MPG.

Short trips does hurt your MPG because the engine has to stay on for a certain amount of time everytime you "start."

FWIW, my work is only 7 miles from home and i run errands all day and drive an average of 40 miles a day.

[thesaintjim]

I drive 80-100 miles a day. 80% being highway travel which includes a lot of hills. I average now around 27.6 mpg which I am very happy with. I personally believe it is how you drive the car which affects your gas mileage.

[pinzabu]

Last tank of gas, at an off brand 87 octane, the first twenty miles 23.0 mpg, today at a name brand also 87 first twenty miles 34 mpg.. what gives..similar conditions city no ac relatively flat..

Currently about 3400 miles on the car. L

[RX400h]

One tip:  check your tire pressure monthly.  I actually increased my tire pressure to 35 (factory is 30 psi).  Less rolling resistance without much difference in handling.  Maybe this is the reason for my high MPG.

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Unfortunately, keeping your tires at 35 psi will likely result in heavy wear at the center of each tire and little wear around the inside and outside of the tread. Your tire life will be reduced significantly and I'm betting that these tires are NOT inexpensive.

[stevskc]

We got our 400h on 7/28 and have drive about 910 miles since. The first 240 was around town, 30/70 highway/city. The average as calculated by the Nav system is 23mpg. The next 670 miles or so was from Palo Alto to Santa Barbara, about 90/10 highway/city. Again, the Nav system calculated 23 mpg. My calculation based on actual mileage and fill-up was somewhat less but close to 23 mpg. My AC is always on. But nowhere can I get 31/27 as per EPA.

One problem I see is that the engine comes on way too soon, sometimes before the car hits 20 mph. And whenver the engine comes on, if the acceleration is gradual, the instantaneous mpg goes down to 8, 15, and stay generally below 20. I suspect that is the main problem. If Lexus can adjust the timing such that the front motor comes on more frequently, perhaps it can improve the mpg.

By the way, we have several cars and on all of them other than the 400h, I am always able to hit the EPA estimate. So I don't think the poor mpg on the 400h is due to my driving habit.

Other than that, we do like the car very much. On the other hand, had I known it does not live up to the EPA estimate by this much, I might not have rushed out to get the car as soon as I did.

[katzjamr]

The hybrid system needs time to break in, and even tho you are experienced in high mileage in a conventional car learning to get the best mpg in the 400h does take some time. Also most of your miles have been highway, make sure you use the cruise control as much as possible as this will also improve mpg. enjoy your 400h and welcome. The majority of us are getting 25 to 27 mpg in mixed hiway/city use.

[jerryray]

The hybrid system needs time to break in, and even tho you are experienced in high mileage in a conventional car learning to get the best mpg in the 400h does take some time.  Also most of your miles have been highway, make sure you use the cruise control as much as possible as this will also improve mpg.  enjoy your 400h and welcome.  The majority of us are getting 25 to 27 mpg in mixed hiway/city use.

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So far I only have 70 miles on my car, mileage is at 24.8

What I have noticed is while in slow traffic, pressure on the accelerator will determine when the engine starts. If I am easy I can get up to 15 mph before engine starts. If I am heavy on the pedal, the engine will always start.

I am hoping to get 26-28, but 25 isn't bad either.

[JasonATL]

What I have noticed is while in slow traffic, pressure on the accelerator will determine when the engine starts.  If I am easy I can get up to 15 mph before engine starts. If I am heavy on the pedal, the engine will always start.

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Without the A/C on, I can usually (when I try) get up to 40 MPH without the ICE starting. With the A/C it varies between 20 MPH and 40 MPH. Also, the dashed white lines on that gauge usually indicate the range for using electric only, from what I've noticed. However, the ICE kicks on more often in the top of that range if the A/C is on.

[jj_fender]

...nowhere can I get 31/27 as per EPA.

One problem I see is that the engine comes on way too soon, sometimes before the car hits 20 mph. And whenver the engine comes on, if the acceleration is gradual, the instantaneous mpg goes down to 8, 15, and stay generally below 20. I suspect that is the main problem. If Lexus can adjust the timing such that the front motor comes on more frequently, perhaps it can improve the mpg.

By the way, we have several cars and on all of them other than the 400h, I am always able to hit the EPA estimate. So I don't think the poor mpg on the 400h is due to my driving habit.

Other than that, we do like the car very much. On the other hand, had I known it does not live up to the EPA estimate by this much, I might not have rushed out to get the car as soon as I did.

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I agree with you 100% Stevskc. The low MPG is not due to your driving habits. I have almost 2000 miles on my RX400h and believe that I will never be able to average over 26 MPG. I just started working about 5 miles away and my average has been dropping. The highest I ever got was 25.2 with no air conditioning, no passengers, and a 30 mile round trip commute. Now with the shorter commute, I am down to 24.6 MPG. The only time I have reset my average MPG (using the Nav system) was after the first tank full. That is because I believe the dealer tested the vehicle pretty hard and killed the mileage. Before the reset I was averaging 22.5 MPG.

People that claim higher mileage must have fairly long commutes. The MPG is simply not what Lexus claimed. I also believed the electric system would work harder. I never see the rear motor come on and the ICE kicks in way too soon. When I saw the avertised 30/27 MPG, I thought the electric would do more work around town. It is a nice concept, but it just doesn't work as advertised.

[thesaintjim]

...nowhere can I get 31/27 as per EPA.

One problem I see is that the engine comes on way too soon, sometimes before the car hits 20 mph. And whenver the engine comes on, if the acceleration is gradual, the instantaneous mpg goes down to 8, 15, and stay generally below 20. I suspect that is the main problem. If Lexus can adjust the timing such that the front motor comes on more frequently, perhaps it can improve the mpg.

By the way, we have several cars and on all of them other than the 400h, I am always able to hit the EPA estimate. So I don't think the poor mpg on the 400h is due to my driving habit.

Other than that, we do like the car very much. On the other hand, had I known it does not live up to the EPA estimate by this much, I might not have rushed out to get the car as soon as I did.

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I agree with you 100% Stevskc. The low MPG is not due to your driving habits. I have almost 2000 miles on my RX400h and believe that I will never be able to average over 26 MPG. I just started working about 5 miles away and my average has been dropping. The highest I ever got was 25.2 with no air conditioning, no passengers, and a 30 mile round trip commute. Now with the shorter commute, I am down to 24.6 MPG. The only time I have reset my average MPG (using the Nav system) was after the first tank full. That is because I believe the dealer tested the vehicle pretty hard and killed the mileage. Before the reset I was averaging 22.5 MPG.

People that claim higher mileage must have fairly long commutes. The MPG is simply not what Lexus claimed. I also believed the electric system would work harder. I never see the rear motor come on and the ICE kicks in way too soon. When I saw the avertised 30/27 MPG, I thought the electric would do more work around town. It is a nice concept, but it just doesn't work as advertised.

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I do around 37 miles which is all highway and I am actually getting better gas mileage now. I average 28.3 mpgwith 1500 miles on the 400h.I coast when I can, don't slam the gas pedal..etc. I live in PA and I do 28 mpg on hills, slopes and mountains

[patt]

I agree with you 100% Stevskc.  The low MPG is not due to your driving habits.  I have almost 2000 miles on my RX400h and believe that I will never be able to average over 26 MPG.  I just started working about 5 miles away and my average has been dropping.  The highest I ever got was 25.2 with no air conditioning, no passengers, and a 30 mile round trip commute.  Now with the shorter commute, I am down to 24.6 MPG.  The only time I have reset my average MPG (using the Nav system) was after the first tank full.  That is because I believe the dealer tested the vehicle pretty hard and killed the mileage.  Before the reset I was averaging 22.5 MPG. 

People that claim higher mileage must have fairly long commutes.  The MPG is simply not what Lexus claimed.  I also believed the electric system would work harder.  I never see the rear motor come on and the ICE kicks in way too soon.  When I saw the avertised 30/27 MPG, I thought the electric would do more work around town.  It is a nice concept, but it just doesn't work as advertised.

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Stevskc and jj, I suggest you look at some of the older threads:

http://us.lexusownersclub.com/forums/index...mileage&st=135#

particularly post 149 which has a good explanation of things that effect mileage. And this one:

http://us.lexusownersclub.com/forums/index...pic=19829&st=30

post 34 has an explanation of why the batteries and motors don't get used more.

Also, take a look at the profiles for EPA city and highway mileage tests on

www.fueleconomy.gov

The highway test is a lot slower than freeway speeds. The city test is probably not much like your off freeway driving either. There are also some ideas of what people are doing to get better mileage on this thread and other threads on mileage. The driving habit I find most important is to anticipate the need to brake and brake gently enough that most of the energy goes into regeneration rather than into wearing my brake pads down.

Our commute is between 15 and 18 miles. With that plus some short errands, we are getting between 25 and 27 mpg per tank.

Instantaeous mileage during acceleration is low - when you start to accelerate, you aren't traveling many miles per second and you are putting in a lot of energy per second. However, you don't do that for very many seconds and only for a small fraction of a mile. When averaged with the lower energy demands during cruising you can still get good overall mpg.

[patt]

QUOTE(lucca @ Aug 7 2005, 11:57 AM)

There is a TSIB (EG010-05) concerning the ISC Learning procedure to re-initialize the idle speed control if the 12v battery dies.

If this is not performed the following may happen:

1. The engine runs too long or more frequently than normal.

2. Reduced fuel economy.

3. Transmission gear "clatter" noise at idle is more pronounced.

I wonder if some of the complaints of poor fuel economy is related to this learning procedure not being performed after a battery dies.

Those getting poor mileage might want to check into this TSIB (from the Rx400h Dead Battery, Warranty thread, http://us.lexusownersclub.com/forums/index...howtopic=22797).

[RolandB]

My 21.06 mpg came at 2,307 miles! 

Odom.      MPG

546 22.27

866 22.89

1,100 21.38

1,409 21.95

1,715 21.14

2,026 22.32

2,307 21.06

This all is calculated and not from the car MPG readings.  I was told to give it 5,000 miles before drawing any conclusion.  Almost all of this was in city with some freeway miles.

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What section of the country do you live in ?? I found that the HOT weather with the AC on really has an affect on the milage. I'm getting 22 -23 in 90º weather. I' not thrilled either

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I'm in Dallas Texas where it DOES GET HOT and the A/C runnnnsssss... Thank goodness. I'm up to 3,400 miles and the last tank calculated mpg was 20.9 (the Energy display showed 21.5 and I reset it with each fill-up) and my lifetime to date is 21.4 mpg! I'd like to try not running the A/C but it's too hot here this time of year! BTW, the display which shows avg mpg since reset is nice but not very accurate! I use an Excel spreadsheet as I did with my RX300. It's rather simple but I input odometer, price per gallon, total $$ and it calculates gallons, mpg for tank, and mpg since purchase!

[rvtravel]

Lexus RX 400h observation

1)When engine is cold, it seems to start and run most of the time until it reaches operating temperature.

2)Fuel consumption: (This area has rolling hills plateau up to 2,000 feet). All mileage checked at same pump, filling to same level.

a.Highway speeds under 70 MPH using cruise control electric motors seem to phase in/out as expected and mileage is 28.1 mpg average. Electric motors stay on a lot even at highway speeds if terrain is relatively flat to slight slop downhill.

b.Short trips to store, 1-2 miles, stop, park then start mileage is about 22 mpg.

c.Small town driving 8-20 miles where speeds range from 30-45 mph with some start/stop the mileage is 27.2 mpg.

d.City driving where there is more stop/go, mpg seems to be better according to the monitor but have not driven enough to evaluate.

3)At speeds of 40 and below on level terrain the RX will run off of the battery for a long distance if there is very little pressure on the accelerator but this is very difficult to maintain.

4)Having the A/C on re-circulate seems to maintain the temperature and the engine does not have to come on as much to recharge the battery

[judyrandy]

In just under 450 miles we are averaging 25.8 MPG with 70% highway, 30% city-like driving. Without breaking in I would say thats pretty good. I'm pleased.

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I am curious Lexbone, do you drive on fairly flat terrain? I noticed that a LX400h owner from Florida seemed to get higher mileage also.

I am now right in between 24.9 and 25.0 MPG and it seems to be a real battle to try to keep it over 25. I am wondering if it is because I live on a hill in San Diego with many hills and canyons.

One thing I am convinced of; the car definately gets better MPG on the freeway. Once a week I take a 50 mile round trip and can get the average up about .1

The LX400h was supposed to get better mileage around town. The fact that it does not is disapointing. The electric motors were supposed to work a little harder and ease the burden on the ICE.

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[katzjamr]

rv travel you are spot on with my experience. how bout some rolling stories, how far have you rolled without hitting the gas to a freeway exit or in another situation, and were the people behind u upset?

[JudyBarbara]

i have a 400h with almost 3000miles. i've just returned from the dealer, where i had the car checked to see if there was a problem with a setting or something, because i've never had better than 24mpg, and it's been decreasing in mpg the longer i've been driving the car. i live in illinois - quite flat - and i try to drive smoothly, without accelerating or braking quickly. A friend with a prius has given me some tips, but i'm pretty frustrated.

i can't imagine what i'm doing wrong to post such poor mileage, but i feel i was taken. Any advice?

i drove an rx300 before, and my husband drives an LS400 and gets the same mpg i do.

[patt]

i have a 400h with almost 3000miles.  i've just returned from the dealer, where i had the car checked to see if there was a problem with a setting or something, because i've never had better than 24mpg, and it's been decreasing in mpg the longer i've been driving the car.  i live in illinois - quite flat - and i try to drive smoothly, without accelerating or braking quickly.  A friend with a prius has given me some tips, but i'm pretty frustrated.

i can't imagine what i'm doing wrong to post such poor mileage, but i feel i was taken.  Any advice?

i drove an rx300 before, and my husband drives an LS400 and gets the same mpg i do.

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You might not be doing anything wrong. Do you know if they did the proceedure in

TSIB EG010-05?

There is a TSIB (EG010-05) concerning the ISC Learning procedure to re-initialize the idle speed control if the 12v battery dies.

If this is not performed the following may happen:

1. The engine runs too long or more frequently than normal.

2. Reduced fuel economy.

3. Transmission gear "clatter" noise at idle is more pronounced.

I wonder if some of the complaints of poor fuel economy is related to this learning procedure not being performed after a battery dies.

[jj_fender]

i have a 400h with almost 3000miles.  i've just returned from the dealer, where i had the car checked to see if there was a problem with a setting or something, because i've never had better than 24mpg, and it's been decreasing in mpg the longer i've been driving the car.  i live in illinois - quite flat - and i try to drive smoothly, without accelerating or braking quickly.  A friend with a prius has given me some tips, but i'm pretty frustrated.

i can't imagine what i'm doing wrong to post such poor mileage, but i feel i was taken.  Any advice? ...

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I personally do not believe that you are doing anything wrong. I have about 2000 miles on my RX400h and the average is 24.6 MPG. I coast whenever possible and do not use the AC even when it is hot. I practice painfully slow starts whenever there are no cars behind me. It is frustrating...the car just does not even come close to the advertised mileage. I expected more than this.

[patt]

i have a 400h with almost 3000miles.  i've just returned from the dealer, where i had the car checked to see if there was a problem with a setting or something, because i've never had better than 24mpg, and it's been decreasing in mpg the longer i've been driving the car.  i live in illinois - quite flat - and i try to drive smoothly, without accelerating or braking quickly.  A friend with a prius has given me some tips, but i'm pretty frustrated.

i can't imagine what i'm doing wrong to post such poor mileage, but i feel i was taken.  Any advice? ...

←

I personally do not believe that you are doing anything wrong. I have about 2000 miles on my RX400h and the average is 24.6 MPG. I coast whenever possible and do not use the AC even when it is hot. I practice painfully slow starts whenever there are no cars behind me. It is frustrating...the car just does not even come close to the advertised mileage. I expected more than this.

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There is a big difference between averaging 24.6 MPG as you are and never getting more than 24 MPG as Judy reports. Averaging 24.6 may be consistant with the EPA MPG numbers depending on how different your driving is from the EPA city and highway numbers. I get the EPA numbers when I drive something close to the EPA profiles. Our average over the life of the car so far is just over 25 mpg though that includes using AC .

By the way, I have found that painfully slow starts don't seem to be the best thing for mileage. I get as good or better mileage when I go fairly promptly up to speed and then cruise. And why would you spend 50K to drive a car where you can't use the air conditioner?

[jerryray]

I was under the impression the Air conditioning compressor is battery operated.

I do believe this is true, so running the air conditioner should not have any effect on the gas mileage. I would agree that in traffic the batterys would last longer with the air off.

comments?

quote=patt,Aug 10 2005, 03:10 AM]

i have a 400h with almost 3000miles. i've just returned from the dealer, where i had the car checked to see if there was a problem with a setting or something, because i've never had better than 24mpg, and it's been decreasing in mpg the longer i've been driving the car. i live in illinois - quite flat - and i try to drive smoothly, without accelerating or braking quickly. A friend with a prius has given me some tips, but i'm pretty frustrated.

i can't imagine what i'm doing wrong to post such poor mileage, but i feel i was taken. Any advice? ...

←

I personally do not believe that you are doing anything wrong. I have about 2000 miles on my RX400h and the average is 24.6 MPG. I coast whenever possible and do not use the AC even when it is hot. I practice painfully slow starts whenever there are no cars behind me. It is frustrating...the car just does not even come close to the advertised mileage. I expected more than this.

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There is a big difference between averaging 24.6 MPG as you are and never getting more than 24 MPG as Judy reports. Averaging 24.6 may be consistant with the EPA MPG numbers depending on how different your driving is from the EPA city and highway numbers. I get the EPA numbers when I drive something close to the EPA profiles. Our average over the life of the car so far is just over 25 mpg though that includes using AC .

By the way, I have found that painfully slow starts don't seem to be the best thing for mileage. I get as good or better mileage when I go fairly promptly up to speed and then cruise. And why would you spend 50K to drive a car where you can't use the air conditioner?

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[patt]

I was under the impression the Air conditioning compressor is battery operated.

I do believe this is true, so running the air conditioner should not have any effect on the gas mileage. I would agree that in traffic the batterys would last longer with the air off.

comments?

And the battery gets its energy from where?

The AC is electrically powered. That power can come from the engine turning the generator directly when the engine is running. When the engine is not running or more power is needed than the engine is generating, it can come from the battery - but all the energy in the battery came from the engine initially. If that energy wasn't used to run the AC, it could be used to get the car moving. At freeway speeds this is a fairly small impact and you may not notice it - maybe 1 mile per gallon. When you will notice it is sitting in traffic with the sun blazing or when you start driving with a hot interior - sometimes the battery will get run down enough that the engine has to run when normally you would be on the motors. At city speeds and stop and go, the impact on mpg is much more noticeable.

Any electrical power used to run the AC, the stereo, the lights, etc. uses energy that came from the engine and otherwise could be used to turn the wheels. It all impacts mpg. The only exception would be when one is going down such a long downgrade that the battery gets full and the regeneration energy would be lost if it wasn't powering accessories.

[JudyBarbara]

i have a 400h with almost 3000miles.  i've just returned from the dealer, where i had the car checked to see if there was a problem with a setting or something, because i've never had better than 24mpg, and it's been decreasing in mpg the longer i've been driving the car.  i live in illinois - quite flat - and i try to drive smoothly, without accelerating or braking quickly.  A friend with a prius has given me some tips, but i'm pretty frustrated.

i can't imagine what i'm doing wrong to post such poor mileage, but i feel i was taken.  Any advice?

i drove an rx300 before, and my husband drives an LS400 and gets the same mpg i do.

←

You might not be doing anything wrong. Do you know if they did the proceedure in

TSIB EG010-05?

There is a TSIB (EG010-05) concerning the ISC Learning procedure to re-initialize the idle speed control if the 12v battery dies.

If this is not performed the following may happen:

1. The engine runs too long or more frequently than normal.

2. Reduced fuel economy.

3. Transmission gear "clatter" noise at idle is more pronounced.

I wonder if some of the complaints of poor fuel economy is related to this learning procedure not being performed after a battery dies.

←

My battery has never died, so I'm sure TSIB EG010-05 has never been performed.