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Rx400h Fuel Economy Getting Worse?


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I am just wondering if anyone else with a 400H is finding there fuel figures getting worse rather than better with time. Even with carful driving I am finding the petrol engine is running 95% of the time hence the Battery is staying fully charged in the green most of the time.

Pushing your foot slightly on the gas pedal, the electric engines engage and then a second later the engine cuts in. In the summer when I bought the car with careful driving I could go for a fair way before the petrol engine cut in.

I am starting to wonder if the electric engines are wearing out ( already) or maybe the engine likes to run while it is so cold, and this wasnt a problem in the summer.

Any thoughts or experince already with this amazing car would be great thanks Mark

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Electric engines are wearing out ?? I think this is rather unlikely.. and that's an understatement...but you're right to note that it is winter and that a car behaves different.

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Just a guess but as it's winter your car needs to power A/C with heat, heated rear window, heated seats, lights, headlamp washers, power to rear wheels in slippery conditions etc. Wonder if it's just a way of making sure the Battery can cope??

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Hi, new round here.

Yes, noticed the same thing - I figured it's because it needs to heat up so you can run your heaters etc. In late summer, I could start and creep out of my drive without the engine kicking in. Now it starts almost instantly.

On a high speed run back from the Alps on Tuesday, I got 24.9mpg :duh:

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it is due to colder days as everyone said, and especially the heater. Try putting it lower so it doesnt have to work too much. I find 20c comfortable and better on the gas.

Good point is that heaters need a lot less to heat up than in an diesel (almost instant).

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Yes I guess, so i tried turning the AC off this evening and it did seem a little better,(not alot) just left the heated seat on Full:-), I am still amazed the difference in MPG bettween winter and summer use, about 4mpg, that is a hell of alot for heating the car, as in the summer surly the Ac is working hard keeping the car cool? When the temp warms up we will see, thanks for all that replied, stoped me going in to my local dealer and making my self look a fool

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Just my two penneth for what its worth.

Maybe the vehicles batteries are not maintaining the peak charge they once could when the car was new.

This could be caused by every day useage, inwhich case it doesn't say much for the duarbility of the cells if they are degrading already, or, it could be the cold weather having and effect on the cells being able to maintain a high state of charge when the car is parked in cold conditions over night. As we all know, batteried don't like the cold and don't deliver the power that they are supposed to when the temperature drops. (certainly the case for lead acid anyway, as well as other Battery types that I can think of.)

All of what I've just said is only my uneducated guess at what might be causing the problem, there again it may be as others have said, just a need for the engine to run to provide cabin heat.........which suprises me that an electric heater was not fitted to prevent the engine from firing up just to simply warm the cabin.

Regards

RxMIke

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Just my two penneth for what its worth.

Maybe the vehicles batteries are not maintaining the peak charge they once could when the car was new.

This could be caused by every day useage, inwhich case it doesn't say much for the duarbility of the cells if they are degrading already, or, it could be the cold weather having and effect on the cells being able to maintain a high state of charge when the car is parked in cold conditions over night. As we all know, batteried don't like the cold and don't deliver the power that they are supposed to when the temperature drops. (certainly the case for lead acid anyway, as well as other battery types that I can think of.)

All of what I've just said is only my uneducated guess at what might be causing the problem, there again it may be as others have said, just a need for the engine to run to provide cabin heat.........which suprises me that an electric heater was not fitted to prevent the engine from firing up just to simply warm the cabin.

Regards

RxMIke

eh, why post assumptions? There is a great deal of technology that went into those batteries to Insure they can last 15 years. Certainly, few months old car is not loosing its charge - it is not an sony cell phone!

This is well known "problem" for all hybrid owners, of all vehicles. And yes, electric heater is fitted however it spends electricity which means engine needs to spin to cover it! Problem is with short runs when most of the trip, car is trying to warm your cabin. Long distance cruising isnt that affected at all. Car assumes that for few mpg, you would preffer to have your arse warm and not chilled, in 30k vehicle :-).

New system in Camry will have an "eco" heating mode which will ease the pain during the winter.

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Having owned a Prius for nearly 2 years, I can confirm that your winter MPG will be considerably worse than your summer figures.

Seems to be one price to pay for the technology, although us poor Prius owners do not get warmed bottoms or heated door mirrors !

There has been considerable discussion on this subject here

http://toyotaownersclub.com/forums/index.php?showforum=52

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Over the Xmas break the Battery on the RX400h drained completely. The RAC man was guided by Lexus over the phone and the car returned to good health.

Only thing - before this, the average mpg was 28/29. Now it is 25.

Is this a coincidence. Or could there be deterioration of the batteries.

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Over the Xmas break the battery on the RX400h drained completely. The RAC man was guided by Lexus over the phone and the car returned to good health.

Only thing - before this, the average mpg was 28/29. Now it is 25.

Is this a coincidence. Or could there be deterioration of the batteries.

I left my car at the airport over the Xmas, If I had an RX400h and done that , and came back to a flat Battery I would be :tsktsk: angree to say the least. :o

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Over the Xmas break the battery on the RX400h drained completely. The RAC man was guided by Lexus over the phone and the car returned to good health.

Only thing - before this, the average mpg was 28/29. Now it is 25.

Is this a coincidence. Or could there be deterioration of the batteries.

Out of interest did you leave the drive selector in "P" ?

Apparently the Battery will only be charged from the main Battery when in this position.

I have left the car for four weeks in damp, cold even snowy weather and had no problem starting it again.

Just wondered

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Over the Xmas break the battery on the RX400h drained completely. The RAC man was guided by Lexus over the phone and the car returned to good health.

Only thing - before this, the average mpg was 28/29. Now it is 25.

Is this a coincidence. Or could there be deterioration of the batteries.

you still relay on "normal" Battery for startup, it has nothing to do with hybrid Battery. Your Battery wont deteriorate for 10-15 years, at least, and you have 8 year warranty on it.

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A good reply from Edinburgh Lexus thanks, I thought the petrol engine, ran ac and heating, in fact I thought the ac and heating were all part of the same unit, I have learnt something there, that they are run from two different power sources. So I will try turning the heat down, to close to Cold and turning the heated seats up and wearing snowboard gloves, No!!!! dont think so:-)

I just read the Prius message board and struth they are talking about Sueing Toyota,struth chaps, steady!!!

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  • 2 weeks later...

I agree with the economy figures for winter/summer. My take on it is that there would be a significant aount of engine wear if it kept starting and stopping when it's cold, so it has to run until normal temperature is reached. With the colder weather (more or less 20 degrees colder than in summer), it takes longer to warm up ... therefore less fuel economy especially if you have a shortish trip to work.

I agree about the engine kicking in too soon - you never seem to get the full benefit of the electric power unless you really are creeping along. Has anyone noticed that if you really boot it from stand still you can almost drain the batteries by the time you get to ...ahem... cruising speed?

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:blush: Guys ALL cars will use more fuel in these freezing conditions, RX400h no exeption, they like all cars take more time to warm-up and the petrol engine must start earlier and stay on longer to heat the car and boost batteries, My A8TDI consumption has gone up 4MPG over this last 2 months, particularly on short trips.

Roll on spring. :lol:

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I've done about 700 miles on a new Rx400h-SL. Brilliant car. To comment on fuel consumption. I have a reasonably light foot and normally expect close to the average consumption in the spec sheet.

Driving around town with a bit of stop/start on the motorway seems to give 33mpg. Longer drive (120miles) averaged out at 35mpg. No complaints as this includes a couple of experiments to see what happened when I put my foot down.

And yes it was cold weather but I suspect there is a technique to getting the best mpg out of this machine.

Oh and in case any one else has had the proble,m motorola V500 mobiles do connect reliably by Bluetooth but you have to load the address book an entry at a time which is a bit of a pain. I blame the phone!

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:blush: Guys ALL cars will use more fuel in these freezing conditions, RX400h no exeption, they like all cars take more time to warm-up and the petrol engine must start earlier and stay on longer to heat the car and boost batteries, My A8TDI consumption has gone up 4MPG over this last 2 months, particularly on short trips.

Roll on spring. :lol:

I agree,all other cars that I have owned have worse economy during cold weather,so there is no reason to suppose the RX 400h will be different.The real question would be : Does the RX 400h's economy suffer more as compared to a non-hybrid car during cold weather?

If it does,I suspect there won't be much in it really.

I have only had my lexus in the cold weather,so I'm looking forward to improving economy as spring comes and the engine runs in.

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