MPG: do ALL Gen 2 Prii PERFORM the same??

With the modern Japanese factory dedicated to 6-sigma and variability reduction, I doubt there is a difference between cars.

You don't hear about "Monday cars" coming off Japanese assembly lines.

 

But on the other hand, there are manufacturing tolerances, which will make a small difference.

I am sure a US model will be different for the EU version for example because we do have different specs and equipment fitted as atandard.

 

"Flat terrain makes for better MPGs" might not hold true for a lead-foot, but I think terrain, driver, and gasoline quality are the major variations.

I doubt non-lemon versions of the car vary that much...

 

I have works on cars my whole life and have never, never seen any two the same. There is variability with any mechanical device and not all the devices in the Prius are from fabled quality manufacturers like Toyota. The batteris come from Panasonic, the electric motors are outsourced to Nippon Denso, ETC, ETC, ETC. Electronics and ECUs are built in factorys using standard components with variability around 10% on non critical components like resistors and caps.
Why do some cars brely pass emission tests right out of the factory while others exatly the same sail through. The older they get the MORE variable they become.
My experiance is the Japanese manufactuers have very good quality control but they all have specifications that they must pass and even these have fairly large parameters with only the worst not making the grade. Usually this failure rate is well known and factored into the final cost of the product. Why are LCD screens above 24" so costly? They have about a 50 % failure rate because they are almost completly hand made and the technology is new. The same is true for our Prius. New technology = more expence and greater variability. Frankly, I'm surprized by the Prius relatvly low price and it's having a better then expected repair frequency but they are far from perfect.
-Paul R. Haller-

 

" ...these have fairly large parameters with only the worst not making the grade."

Your observation appears to fly in the face of 20 years of analysis of Japanese manufacturing methods, and Toyota's in particular.


"The batteries come from Panasonic, the electric motors are outsourced to Nippon Denso, ETC"

Again, the history of Toyota, documented in dozens of books and articles, indicates that they hold their suppliers to their own standards of quality.


"variability around 10% on non critical components like resistors and caps."

This is on the values of the individual components. In a digital device these do not have any effect at all on the output.


"...almost completly hand made and the technology is new. The same is true for our Prius"

Where have you read that the Prius is hand-built?

 

I believe that the factor causing the greatest variation in mpg values might be in the type of city driving one does. I sell the Prius and drive in quite a few but I dont drive the multi miles that most owners do so my comments might be suspect.

In driving a lot of them I do notice that performance and INITIAL mpg values seem to be similar. But as reported here and elsewhere.. if one only uses the Prius for short in-town trips which doesnt allow the vehicle to warm up and the battery to charge up then the mpg values might be stuck in the mid 30's. I can see that someone expecting to get 60 mpg EPA in the city might be disappointed.

OTOH those that do a lot of highway driving almost always report mpg values right around 50. Of course weather, terrain and driver input have a significant impact also.

My belief is that it is QUANTITY of miles driven which is the key factor in attaining the rated EPA values. I have one customer that is in his car 8-10 hours a day. He almost always reports 50 mpg +/- on an annual basis. If one drives 6000 annually in only short trips I'd guess the mpg values would be ~35.

comments?

kdhspyder

 

The last 2 Japanese built autos I bought had really glaring defects that needed correcting right off the showroom floor. The last, a 98 Honda Civic required a new manual tranny after less then 50 miles< synchros bad in 3 of 5 forward gears> and my 97 Toyota pickup needed a new head gasket driving away from the dealer the first time. I still bought another Japanese car because I do think they are still better then the domestic cars. But my example shows that they are variable and have major defects despite their sterling reputation for quality.

I was a certified Volvo mechanic working my way through college and later in graduate school, I was a Toyota and Honda service writer. I have seen my share of problems with Japanese cars. Honda, in my humble opinion, falls all over itself to keep customers happy especially if the service writer goes to bat for them as valued customers. That has not always been the case for me with Toyota. Remember the blown head gasket in the Toyota? That was a common problem well known to Toyota. They would not honor a second head gasket so I had to install that one on my own. Still, it was one of the best most reliable cars I have ever owned but I have had consistant problems now with the new dyno smog test getting it to pass.

I don't work on cars much anymore, thankfully, but cars still need work and the japanese cars don't have magic pixie dust sprinkled over them to prevent failures or variability and they are not built in some fancy, no problems line that no other manufacturer has access to. They have the same problems that have plagued all auto manufactuers for ever. The reason I buy Japanese is that these problems seem to be fewer then domestic and their parts prices when the car does need repair, remain somewhat less expensive then European imports. I still stand by my original premise that they are not perfect and are variable.
-Paul R. Haller-

 

I voted item 4, but the right answer wasn't in the poll for me.

I expect the cars are all very close, mechanically. There are two things that I expect may make mpg differences that are noticable:

First the batteries have some variations in impedance, and the lucky owners get the lowest impedance ones, and the better matched sets.

The second thing is all the code updates affecting the hv ecu and engine ecu. The stuff they are changing there has to affect mpg, esp if it affects battery protection set points.

I've read a lot here about how the early cars got better mpg. I think it is true, since I never see even momentary mpg readings like some people get on the highway.
I get at steady 60 what others report getting at 70 mph.

I'm hoping the recall will make mine better when they reprogram it.

Then there is the issue of whether everyting really works. Like others report how noisy the battery blower is, but I've never heard mine come on. Could it be defective? Or are some coming on earlier than needed? I may have to locate the temperature control and test this!

I can see driver techinque making big differences at slow speeds, but on flat high speed highways going at steady 55 or 70 or whatever, I don't see how technique alone can explain the ranges reported, after adjusting for temperature.

 

There was a post where someone bought a 2nd Prius shortly after getting his first one. Not sure if one was a classic, but he drove one, his wife drove the other, on an extended trip. They ended with the same MPG on the display.

 

Most customers were very good and I had a deeply disturbed following by some but there were a few that I couldn't help at all. No one could , but they were definately a minority.
My most memorable circumstances happened as a green Volvo mechanic. They gave me the worst jobs. Like find the awfull smell in a 240D. I tore the entire interior out trying to find a really bad smell. It ended up being a dead rat in the fresh air plenum below the dash. Or the guy who had a diesel that would have is car towed in because it wouldn't start 6 different times. Every time I looked at it the fuel lines were all ground up like they had been put in a meat grinder. We could not figure it out. We finally found out that squirrels liked bio diesel. Who knew, but they were chewing the hoses to get to the bio diesel. We switched over to petrolium diesel and no more squirrles. :huh:
Now, I only work on a car if I must and then only under duress. I do have my Pride and Joy that I like working on. I spent 5 years restoring it to better then factory new. It's a 1970 Pontiac GTO Ram Air 4 with a 455 and a 4 speed in Hugger Orange. It makes better then 400 horses as measured on a dyno. No, it's not a like my Prius cause it does not get 45+ MPG and you HEAR it coming before you see it.
Now that I think about it, I bought the Prius to maybe break even when you weigh the gas gusseling, tree killing, air polluting, GTO against the planet saving, tree hugging ,wife pleasing Prius.
-Paul R. Haller-

 

I think more importantly, MPG is affected by about a thousand different factors, of which maybe like 20-30 are significant. I'll list off a few, in what I believe to be order of importance :

1. Tire Pressure
2. Driving Style
3. Weather/Temperature
4. Road condition
5. Traffic conditions
...
23. Manufacturing variances

Given that 1-5 usually aren't discussed in any relevant detail (lots of potential variation there!), skipping down to manufacturing issues as a root cause is a bit disingenious.