Fuel Consumption Rx400h

[queensberry]

we own a rx400h, about 30 months old (June 07 plate). Had it from new and its done 30k miles. We love the car, well the Mrs does as she drives it the most. She's a very careful driver, very soft on the pedals. Consequently until the last few months she was regularly achieving 32-35 mpg on a mixture of driving - dual carriageway, local, stop start stuff - even in the winter. The last few months, though, she is lucky to get 29 mpg. We wonder if there may be something up with the batteries?

Has anyone noticed something similar?

And what is this I have read somewhere about acetone?

Any helpful comments gratefully received.

[Dan's]

we own a rx400h, about 30 months old (June 07 plate). Had it from new and its done 30k miles. We love the car, well the Mrs does as she drives it the most. She's a very careful driver, very soft on the pedals. Consequently until the last few months she was regularly achieving 32-35 mpg on a mixture of driving - dual carriageway, local, stop start stuff - even in the winter. The last few months, though, she is lucky to get 29 mpg. We wonder if there may be something up with the batteries?

Has anyone noticed something similar?

And what is this I have read somewhere about acetone?

Any helpful comments gratefully received.

could just be dow to the cold weather to be honest i would't be too concerned my friend.

[Great Dane]

Think you are in the "normal" consumption bracket. We run our RX400 in the Algave half of the year and get max 32-33 miles/gallon in the much warmer climate. In the UK (at present) we get 27-28 miles/gallon (mixed driving at both locations).

[Neil Morphett]

Yes, that sounds reasonable. Although the petrol engine is theoretically more efficient in the cold, I guess it takes longer to warm up and cools quicker, the hybrid drive uses the engine more if the engine's cold to warm it up. Also I would not be surprised if the Battery is less efficient when it's cold (I doubt it's heated under the back seat) and add to that you're probably using power for heated seats, windows/mirrors etc, and maybe leaving the car idling for a few minutes to demist/defrost... all adds up. Over the same routes, you do tend that in the winter the engine cuts at times when the Battery is taking the strain in the summer.

I haven't reset my economy gauge since delivery in May 08, and over 20,000 miles this long-term average peaked out at 30.3mpg (end of autumn in '08, after I'd worked out how to drive it most efficiently), then went down to about 29.5 by the spring (winter driving), back up to 29.7 over what passed for summer last year with some long A-road trips, and then hit 29.4 a few days ago after pottering around locally in the cold, snow etc. So I suspect my short-term fuel economy is low 30's in summer and mid-upper 20's in winter.

[queensberry]

Thanks all for your contributions. I reckoned this would be the case but 'er indoors is convinced there must be something wrong since in winter 07 and 08 fuel consumption was a lot better (but then those winters were milder). Anyway, thanks again for your input.

[JBPRX400h]

Thanks all for your contributions. I reckoned this would be the case but 'er indoors is convinced there must be something wrong since in winter 07 and 08 fuel consumption was a lot better (but then those winters were milder). Anyway, thanks again for your input.

Hi

Just a thought. Has the 12v Battery been disconnected or have the Battery volts dropped below about 7v in the recent past?

There has been some discussion about this on the US LOC forum especially by Lemon in Ontario in Canada where they really do have cold winters!

Here is the link to the subject.

http://us.lexusownersclub.com/forums/index...showtopic=58930

The procedure sounds complicated but is actually quite easy to follow and easy to do.

Another reason for higher MPG in the cold weather is that the engine must run more often to keep the catalytic converter up to its correct operating temperature.

Hope this helps

JBP

[Mr Pants!]

Mine has dropped off, but I put it down to having the heating all the time and occasionally putting on my heated seats.

In the summer my engine is off by the end of my road, in the winter the engine stays on long enough until I have a warm cabin. I normally have my temp at 22.

I have to say I have never seen 35mpg in my car and I am very light on the throttle and careful how I drive. I consistantly get 30mpg and have gone down to 29mpg.

[Takis]

Yes,this happened to me too,twice! Consumption is higher during winter especially when it is very cold.(Have you checked tires pressure anyway,if less it usually adds up a lot).

Problem was solved with the annual service,the consumption felt down.9,5-10 lts before 8,5-9 after the service.