Hybrid And Rx400h Tutorial

[bikeandsail]

As an engineer I have read a lot of discussion on this forum about the RX400h and have found that very few people have the foggiest idea of how a hybrid works and what gas mileage is to be expected.

The US government EPA mileage tests are a government requirement that all manufactures that hope to sell cars in the USA MUST do. The tests are performed by the USA government not the manufacture.

The US has also done extensive testing of hybrid cars with several 100,000 miles accumulated with detailed records of gas mileage and maintenance on just the Toyota Prius. If you review these records it is obvious that the US mandated EPA mileage tests produce unrealistically high numbers for the at least the Prius. The actual mileage achieved in several 100,000 miles of driving is more like an average of about 45 mpg or about 20% less than the average mixed EPA rating. Being an engineer I studied this data before purchasing the Rx400h and determined that any average mileage over 23.5 mpg would exceed the long term comparable mileage actually achieved on the Prius. I am so far exceeding that mileage and pleased.

There are several government web sites that have this kind of data but the one below gives the maintenance and mileage results of actual test vehicles, not manufactures data and not the unrealistic EPA data:

http://avt.inel.gov/hev.shtml

One of the things that caught my attention was the very high reliability of the Prius at even 100,000 miles per car usage. I suggest that anyone who is still unsure of whether the Rx400h is a car they want spend some time on this web site before deciding.

The Japanese Toyota site has a very good description of the Prius technology links below:

http://www.toyota.co.jp/en/tech/environment/

Another useful link is this model that explains how the continuously variable transmission works:

http://homepage.mac.com/inachan/prius/planet_e.html

Another link with info:

http://www.eere.energy.gov/cleancities/hev...components.html

Unfortunately the same type of technical information is not available for the Rx400h but the technology is virtually the same.

I guess I am lucky that $55,000 was enough of a dent in my pocketbook that I did my homework prior to purchase. I suggest everyone else do the same.

This vehicle is my first new car since 1976 and I am thrilled with it.

Ron

[RX400hGirl]

Ron -

Thanks for all the links - I have A LOT of reading to do :D

[patt]

Some additional reading.

http://www.fueleconomy.gov/!Removed!/ratings_description.shtml

This is the US site on fuel economy ratings. It has explanations of what they test and how that deviates from real world fuel usage.

They also have a part of the site where people can report their actual mileage and you can view those reports. I looked at a few and the real world was always below the EPA estimate.

Remember one difference between the test conditions and real world is that they don't run any of the accessories like air conditioning and audio system during the test. As a car becomes more efficient at moving itself, the accessory draw will become a bigger percentage of its power usage and will therefore cause a larger variation in the mpg number between the test and real world. I think this is part of the reason that numbers for the Prius have a bigger difference than numbers for a Camry or a Highlander. (No RX numbers were posted.)

[bikeandsail]

Patt,

Where did you find the "real world" numbers that people acually report on the site? I looked and couldn't find them?

Ron

Some additional reading.

http://www.fueleconomy.gov/!Removed!/ratings_description.shtml

This is the US site on fuel economy ratings. It has explanations of what they test and how that deviates from real world fuel usage.

They also have a part of the site where people can report their actual mileage and you can view those reports. I looked at a few and the real world was always below the EPA estimate.

Remember one difference between the test conditions and real world is that they don't run any of the accessories like air conditioning and audio system during the test. As a car becomes more efficient at moving itself, the accessory draw will become a bigger percentage of its power usage and will therefore cause a larger variation in the mpg number between the test and real world. I think this is part of the reason that numbers for the Prius have a bigger difference than numbers for a Camry or a Highlander. (No RX numbers were posted.)

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[SW03ES]

Thanks for the research!

[scoobie]

Patt,

Where did you find the "real world" numbers that people acually report on the site? I looked and couldn't find them?

Ron

I just looked at the site, I would guess the "Your MPG" link is where you can record your real world mpg, but it seems you have to register first.

[patt]

It is under Your MPG. You have to register if you want to put estimates in. To see the estimates others have put in, click on

Real World MPG Estimates from Drivers Like You

at the bottom of the left-hand column. You don't have to register to see this. I like to refer people to upper level web pages rather than more specific pages down the tree because they can move when sites are restructured. I hate getting dead links.

[bikeandsail]

It is under Your MPG. You have to register if you want to put estimates in. To see the estimates others have put in, click on

Real World MPG Estimates from Drivers Like You

Found it Thanks Patt