Rx400h Not Up To Specs

[WEast]

The regenerative braking is one of those things that I think is great about the design. It would take a while to get used to the fact that I'm charging the batteries instead of wearing down the brake pads...

[jerryray]

15 Minutes of traffic, that's it.

I would think there is more reserve than that

Do all the other RX400 owners find this to be true as well?

Just remember that even in stop and go, the battery will run down in 15 minutes, and the gas will kick on...no matter what you do...the battery has to keep a certain amount of charge...

Headless

[patt]

Jerryray, did you read what I wrote? There isn't any payoff in having a large battery reserve. There is a cost - more weight. For efficient operation, you want a battery large enough to:

provide enough empty space to store energy regenerated by braking during normal conditions

provide enough storage for that extra boost for acceleration

provide enough cushion between those two so that when the engine is cycled on for recharging it can be on long enough for efficiency.

Once it is large enough for that, the diminishing returns of more efficient on cycles for the engine would be wiped out by the cost of carrying the extra weight.

All the energy in the battery comes from running the engine. You can't get past that. You can only design so that that energy is generated in an efficient operating mode for the engine.

[the-headless_horseman]

15 Minutes of traffic, that's it.

I would think there is more reserve than that

Do all the other RX400 owners find this to be true as well?

Just remember that even in stop and go, the battery will run down in 15 minutes, and the gas will kick on...no matter what you do...the battery has to keep a certain amount of charge...

Headless

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The engine only kicks on for a minute or two or three...it will take away about 1 mpg on your meter...then again, this depends on how far you've traveled...if you happen to be in bumper to bumper traffic and get a few 'breaks' along the way, once you get up a little speed, the coasting will help prolong the battery charge...

Headless

[patt]

Today for the first time, I had to do a lot of driving (a total of about 40 miles divided into about three trips) on suburban surface streets - lots of lights moderate traffic. I was surprised to see multiple 5 minute intervals on the consumption screens where I did between 30 and 40 mpg. There was even one stretch along a 40 mph road with a couple of lights where the interval was over 40 though I think that stretch of road has a very slight downgrade. There were also some around 25 mpg particularly at the start of a drive -even though the engine isn't on all the time once one is driving, it seems like starting out cold it gets much worse mileage. Maybe it helps efficiency to not have too long between times that it cycles on in slow stop and go so it stays warmed up.

I hadn't reset the cumulative mileage meter, but from a rough calculation based on how many miles I drove and how much improvement there was in the cumulative mileage, I was getting a little over 30 mpg over the 40 miles.

I didn't worry about whether the engine came on for acceleration. I did normal non-jack-rabbit starts like one would trying to get good mpg with a conventional engine. I was careful to watch for red ligts and start decelerating ahead of time so that the regeneration could function.

[lexusgolf]

New to this forum. We have a 2004 RX330 and recently received the 400h. We think that the steering on the 400h is much tighter than the 330. To the point of almost feeling like it doesn't have automatic steering. Has anyone noticed this and any comments??

[skyfish400h]

New to this forum.  We have a 2004 RX330 and recently received the 400h.  We think that the steering on the 400h is much tighter than the 330.  To the point of almost feeling like it doesn't have automatic steering.  Has anyone noticed this and any comments??

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I noticed that on my brief test drive... I like it!

[patt]

I agree with Skyfish. I like the responsive steering. I wouldn't say it is "almost to the point of feeling like it doesn't have power steering." If my recollection is correct, I think I read that it isn't even a direct linkage but is some sort of steer by wire.

It has performed really well in our recent rains.

[skyfish400h]

For efficient operation, you want a battery large enough to:

provide enough empty space to store energy regenerated by braking during normal conditions

provide enough storage for that extra boost for acceleration

provide enough cushion between those two so that when the engine is cycled on for recharging it can be on long enough for efficiency.

Once it is large enough for that, the diminishing returns of more efficient on cycles for the engine would be wiped out by the cost of carrying the extra weight.

←

Actually, battery sizing is pretty simple. There is really only 4 variables and weight is not one of them (directly). Power, time, system losses, and a factor called Depth of Discharge (DOD) are the key players.

The size of a battery is measured in Watt Hours (how many hours it will provide a given amount of energy - Watts). Once that is established then comes the packaging and weight concerns. These are a function of the battery material technology and are related to the DOD factor I mentiond. NiCads wear out faster then Ni-MH by nearly a factor of 2, so a lot of weight is saved right there.

The real driver is the DOD value. To make a battery last for 100K miles it has to endure a lot of cycles. The greater the number of cycles the smaller the DOD value because you don't want to wear it out. Basically, lots of little changes in charge over many cycles (400h) vs great changes in charge for relativly few cycles (say, I donno, disposable camera). Small values for DOD drive up the W-hr size of the battery and, by extension, the weight.

So, long story short, the 400h IS carring around a lot more battery than it needs on any given day, but it has to carry that much so that you won't be in for a new battery every oil change.

Now changing a much smaller battery every oil change would be a viable scenario and would reduce the vehicle weight, but I'm sure the minds at Toyota decided that even if it was economically workable, the customer would not accept it from a reliability point of view.

[speedyg]

New to this forum.  We have a 2004 RX330 and recently received the 400h.  We think that the steering on the 400h is much tighter than the 330.  To the point of almost feeling like it doesn't have automatic steering.  Has anyone noticed this and any comments??

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Tighter? I found it to be on the loose side (i.e. doesn't take a lot of force to turn) compared to my other vehicles. If you've driven cars that don't have power steering and your RX400h feels like that, then there is something wrong with your RX400h.

[kmke]

We've got over 600 miles on our RX400 - average 24 to 25 mpg - we are disappointed that the gas motor runs so much - regardless of how gingerly we accelerate - and the batteries are never fully charged.

Average trip roughly 20 miles - frequent start and stop. We were led to believe that once warmed up - all electric up to 30 mph - not our experience.

We are also surprised to see how often the electic is engaged - were told that anything over 55 was purely gas unless slippage in the drivetrain or a heavy acceleration demand. Set the cruise - level road, and the electric comes in and out without any sense of why. Clearly some tuning issues we are hoping are computer programmable.

Other than this we love the car - traded a 2004 RX330 that average 20-21 mpg.

kmke

[the-headless_horseman]

We've got over 600 miles on our RX400 - average 24 to 25 mpg - we are disappointed that the gas motor runs so much - regardless of how gingerly we accelerate - and the batteries are never fully charged.

Average trip roughly 20 miles - frequent start and stop.  We were led to believe that once warmed up - all electric up to 30 mph - not our experience.

  We are also surprised to see how often the electic is engaged - were told that anything over 55 was purely gas unless slippage in the drivetrain or a heavy acceleration demand. Set the cruise - level road, and the electric comes in and out without any sense of why.  Clearly some tuning issues we are hoping are computer programmable.

Other than this we love the car - traded a 2004 RX330 that average 20-21 mpg.

kmke

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What you are saying sounds about right...

I think some on this board are accelerating rather slowly...if you accelerate and the gas kicks in, as it should when you actually try to keep up with traffic, you're going to get normal mileage...

Those that are saying 30, 40 mpg, etc...I don't see that in real world driving...maybe coasting on a deserted road, but in higher traffic areas, stop and go on roads around 45 mph will put a demand on the vehicle for the gas to kick on...your mileage will suffer...but you'll still get around 25 mpg...

As far as highway, the electric will kick on to maintain speed...if you go up a hill, the gas will kick on...this is normal...

Expect about 28 mpg at 60 mph, about 25 at 75-80 mph...this is still very good mileage...only on the stop and go heavy traffic on I-95 did I see numbers over 30 mpg...

Headless

[WEast]

Prius owners have maintained that the more miles logged, the more the electric motors stay on and the engine stays off. Is anyone noticing the electric running more often at slower speeds on the 400h yet? Total mileage?

[patt]

kmke, What do you think you will get from the batteries being fully charged?

In usual conditions (unless perhaps you live in the mountains) you will not see the battery fully charged. The hybrid system always wants to leave some headroom in the batteries to store energy when you brake.

The manual says that about the only time you will see the top bar in the battery charged is when you are going down a long hill so that continuous regeneration fills it.

The engine comes on for a number of reasons including to "make heat available for the climate control and emmissions systems." The system will choose a mix of electric and gas to drive the vehicle depending on a lot of factors. You don't have to worry about which it is choosing.

What lead you to believe that it would be all electric for acceleration up to 30 mpg? I haven't seen anything in the Lexus literature that suggests it. "Normal acceleration - MG2 and the engine drive the vehicle."

The quotes are from the little "Hybrid Overview" that came with the RX400. Try reading it.

We got a bit under 25 mpg on our first tank. On our second tank we are seeing the mileage creeping up - getting close to 26 averaged over the tank so far. City driving once warmed up (after the first 5-10 minutes of driving) I've seen 30 mpg. Super slow acceleration and worrying about whether the electric or the engine is powering the car doesn't appear to help mileage. Being careful to brake gently for maximum regeneration where possible does help.

[SW03ES]

and the batteries are never fully charged.

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The batteries will never be fully charged, they're supposed to be niether fully charged nor fully drained. In normal usage you should never see a full battery meter and if you do, only for a short time.

[RX400h]

What lead you to believe that it would be all electric for acceleration up to 30 mpg? I haven't seen anything in the Lexus literature that suggests it. "Normal acceleration - MG2 and the engine drive the vehicle."

Patt, more than one of the articles I have read in car magazines have stated that the RX400h can be powered by the electric motors up to 30-32 MPH. I was a bit surprised to learn in the literature received with the RX that the actual number is 20-22 MPH. Our first tank yielded 25.4 MPG and I am monitoring the usage periodically.

[SW03ES]

It CAN be powered up to that speed on electric motor only, doesn't mean depending on your usage and the environment that it WILL be.

[patt]

Unfortunately, articles in magazines don't always get things right - I know that too well from experience in my own field. I don't have it in front of me at the moment, but I think the hybrid overview says 10 - 15 mph for electric only with the caveat that even then the engine may turn on depending on conditions. I think that was for acceleration.

From my own driving experience so far, I have seen it go to electric only for a while when cruising under 30 mph and even occasionally at 40 and higher. When it wants to dump charge out of the battery, it will. It even went all electric cruising on the freeway today for a short time but it was slightly downhill so not much power was required to maintain speed.

[dreamchaserflorida]

Hello to everyone. I just bought a 2006 RX400h two days ago and my daughter bought a 2006 RX400h three days ago.

I will post our experiences regarding availability on another thread.

Regarding fuel consumption of the RX400h, it is too early for either of us to know what that will be. However, as a Prius 2004 owner, I have participated in Prius message boards for several years and the Hybrid Highlander message boards (I have been on a WaitList for HH for several months).

In the Prius forums, it is acknowledged that the EPA rating procedures for hybrids are faulty and the mpg ratings are usually not extremely accurate. The 51 - 60 mpg range likely will not be reached. Our Toyota dealership salesman pointed this out when we bought but we already knew this.

We usually got 47 - 50 mpg in the city but we run the A/C most of the time a lot of each year because we live in very sunny and hot SW Florida and this reduces the mpg. Also, we have used the Prius in a small city doing short term errands and this reduces mpg.

We all know that driver styles affect the fuel consumption greatly. Personally, we are not the "stomp on the gas pedal and speeder" types so this helped us get better mpg. Even so, we did not reach the better fuel consumption levels of Prius owners who were very diligent in their efforts to attain high mpg levels. We live in a flat terrain area so our consumption differed from others in hilly or mountainous regions. I don't know that this is true but I have the idea that drivers in the cold winter areas get slightly worse mpg than those of us in the humid and hot areas.

Significant factors in mpg are the size, weight and performance of the hybrids and I recognized that the 400h would have slightly poorer reports than other hybrid SUVs especially those like the Ford Hybrid Escape which is smaller, lighter and less powerful. Even so, I wanted the RX400h after I saw it and test-drove it.

I imagine that we will get close to 26 - 28 mpg in the RX400h after the "break-in" considering many factors and I expect very slightly better reports with the Hybrid Highlander if we buy one later for another family member.

Even if we don't get 26 - 28 mpg in the RX400h in city driving, I think that the positive difference in quality, comfort, safety, appearance, and noise abatement as offered by the RX400h was the essential reason for choosing it over any existing comparable hybrid SUVs. I doubt that we will ever buy anything other than a hybrid tech car in the future based on our satisfaction with the Prius and. hopefully, with the RX400h.

dreamchaserflorida, A. B. (A Blonde)

[jj_fender]

So far, I have only put about 300 miles on my RX400h and have filled up once. The average MPG shows 22.3...but is going up slowly.

Two days ago I had an interesting experience. I drove about 22 miles (all freeway) to a meeting. After about 4 hours, I made the return trip. About ten minutes into the return trip I saw an electic sign next to the freeway that said "PREPARE TO STOP." It is a good thing that I slowed down because the traffic came to a halt around the next bend. A cement truck had rolled over and was blocking several lanes.

I was in a stop and go traffic mess for about 30 minutes. At one point it took about 10 minutes to go two miles. During that time the gas engine never came on...it ran on all electric. What a great feeling...knowing that you are not sitting there running a gas engine while heating up and polluting the environment. I think this is one of the main reasons I bought this car. So far, I love it.

Hope the mileage gets better though. :)

[Ron O]

I bought the car for the anticipated performance increase as much as for the potential increase in mileage.

I owned a RX 330 that I bought in October 04. I am please but as you state, I have not got more than 24-25 MPG. And that’s with babying it a bit. I now have 300 miles on it and feel that the whole gear train and motors have yet to bed - break in.

Well see.

How about a turbo Diesel like they have in Europe, 30 -40 mph with high torque 350 –400’ lbs.

I understand that 50% of the Audis are sold with this power option.

Bottom line I’m happy.

[rail88]

I've had my RX400h for about two weeks. Got 27.9 mpg on the first tank and 28.5 mpg on the second tank. A/C runnning the entire time, although the weather hasn't been very hot. I estimate that I drive about 70% highway and 30% city. Most trips are 20 minutes or longer. For reference, I averaged 20.3 mpg in my 1999 RX300 doing the same type of driving.

So far, I'm a very happy camper.

[Ron O]

Re justifying the difference in price between the 330 and the 400.

Every one seems to forget the $$ return when you trade or sell the 400. The increase in price will be reflected in the sell/trade value and so I just discount the difference. ..

I'm most impressed with the performance - pick up etc than the mileage.

I find it is a much more fun car to drive.

Ron O

[jj_fender]

OK...here's the deal on my White/Beige RX400H. I just put a little over 500 miles on the car and filled the tank for the second time. I had not reset the average MPG until today at the gas pump. Up until that point the Average MPG read 22.7.

But this included whatever the dealer did during test drives. Between the last fill-up and this one, I traveled 302.9 miles which took 13.0 Gallons. That is exactly 23.3 MPG.

After this last fill-up, I reset the Average MPG using the NAV System. I decided to baby it a bit to see if I could get the mileage up. The first part of my trip around town actually recorded 33.4 MPG Average but by the time I had run my errands and retured home the Average MPG was back down to around 24 MPG.

I am really trying to get good mileage. I do not gun the engine or run the air conditioner. But I have a hard time believing people who say they are getting over 27 MPG. This car has a lot of "breaking in" to do if I am going to reach these specs. :(

[dreamchaserflorida]

conditioner.  But I have a hard time believing people who say they are getting over 27 MPG.  This car has a lot of "breaking in" to do if I am going to reach these specs.    :(

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We have not driven our RX 400h more than 200 miles so we do not have any realistic data to look at for fuel consumption. We only have used it for very short city drives such as grocery shopping while always using the A/C. We have gotten a little over 23 mpg so far.

However, I do not feel that this is the time to look at fuel consumption considering the many times we have run the car in Park while waiting for someone or that there were other times of poor conditions for higher mpg. So, we won't be in a rush to "fill up". However, I am curious to check the mpg after the first fill up and also after a certain "break in" time.

I will ask my daughter about her mpg in her new RX 400h since she drives it more in the city and just returned from a highway journey of about 250 miles. However, she has only had her car for about ten days (like me) so I don't expect any data which is meaningful because it is too early.

We had guessed that we might get about 28 mpg in this car because we knew that the EPA ratings are usually higher than what is realistic. If we had wanted better fuel consumption, we would have bought a less powerful and heavy hybrid car.

It is going to be interesting to see "the numbers" on the hybrid Highlander when it is available in June. I don't look at the numbers on the Escape Hybrid because it is not really comparable to the Lexus RX 400h.

Yes, I will be disappointed if my mpg is much less than, say, 27 - 28 mpg but right now, I will be patient.... it is just too early to know how efficient my car will be.