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Hi All:

___I took my parents 2010 Prius in so the local Carmax could write up a ticket… Not that we had to bring it in but they wanted it empty? Ok, took some numbers and then we went and filled it back at the station near my parents home. I had my mom send in her spreadsheet for the entire year showing 5,000 miles worth of tanks and all but 2 with an average of almost 6 mpg discrepancy between acutal and FCD. That was that.

___The tech handling the issue was knowledgeable while another next to him thought you could EV forever and screw up the FE calc’s on every tank. I told his boss he did not understand how a hybrid worked and the discussion degraded from there. It was tough to get across to the techs the difference between Trip A/B FE and Trip A/B Odometer Distance.

___Anyway, wasted most of the morning and afternoon with that just so we could send the spreadsheet in and document the Toyota induced error as first discovered at the Press Launch over a year ago.

___Good Luck

___Wayne

Is it a +6 flat error, or is it a % error that happens to be 6 mpg at this operating range?

Mine (bought new in mid December 2009) runs about a 5% error FWIW. Our mpg got as low as 40 in short drive, cold snowy winter, and has been as high as 60 mpg actual per tank. The error fluctuates in amount and percent, but ours is about half what the Gerdes-mobile sees.

Well, we have roughly 6000 miles on our after having picked it up in early August of 2009. The first couple of tanks were almost dead on in accuracy while every other fill-up since then has evidenced a disturbing but already familiar MPG trend as well.

In liters per 100/km, we observe a 0.1 to 0.3 difference in the winter months while in the spring/summer months the discrepancy can vary from 0.2 to as much as 0.5.

While it may not be entirely related to how we drive the car (greater FE error when striving for higher FE as I assumed) I do see the error factor diminish as the ICE in ON more often.
This summer I plan to put the new Prius through a great deal of mostly highway driving and I would really like to see what the overall displayed FE error is.

In the meantime, my wife calls the Prius "a friend that makes you feel good while it fibs in your face".
Conversely, the HCH-II is equated to a mean Sargeant that tells you... that you, your mother, your dog and your mileage skills suck... but then it rewards you with "honors" at the pump with a silent smile.

Awesome cars I tell you. Never dull. :D

Cheers;

MSantos

Our 2006 Prius display ALWAYS ends up showing 3-4mpg HIGHER than actual measured MPG.

I actually do the numbers every tank, and reset the tip meter every tank. The display says 43mpg-calculated is 40 mpg.

This has been from the beginning- 41,000 miles later same story.It is 3-3.5 mpg optimistic.

I wouldn't complain if I got 3 mpg better than display.
I think it is INTENTIONAL!! Toyota wants you to think you're doing better than you are.

It gets great mpg- 80% better than the Corolla it replaced(my wife got 23mpg with it-13 mpg with the Pilot-obviously she isn't a hypermiler). But the display LIES!

Charlie

Ignoring the fuel spill or MFDs I'm not certain of I've the following errors as Pump/MFD%, where measure at pump is trip/gallons:

5.15%
4.92%
6.46%
3.64%
3.80%
4.58%
4.31%
4.04%
5.06%
5.09%
7.24%

(Earliest tanks first)

Hi All:

___My parents 10 Prius is now approaching 1-year and has a touch over 5,000 miles. Their "actual" lmpg is 48.6 while the MFD is on averaging reading 6 over across each tank. I did a top off to top off fill, full tank drive with mostly my parents standard drive and me adding a few miles. At the second top off, there was a 6.1 mpg over report.

___This is really really old news as I found it all the way back at the NAPA Valley preview on the first Prius’ in country and have discussed it any number of times here at CleanMPG. Later FCD’s have been ~ 3 and even later ones have had 0 mpg offsets as well… I simply got around to making a report to my parents dealership about it is all. I believe Mike Sirach and Jud have reported their FCD' are ~ 6 mpg over actual to their respective Toyota dealerships as well.

___Good Luck

___Wayne

I gave up on logging. My wife refuses to record anything when she fills. We have almost 19,000 on it now and it is still consistently in that range. Her FCD is reading 52 to 53 now that summer temps have arrived. I have "B" trip set to record long term. It rolls back to 0 at 10,000 miles. I was driving it a month or so ago when it rolled and have a camera pic somewhere. It was at 54.4 I think. The overall would have actually been considerably less if I could have figured it accurately. If I get to drive a tank, it is always 5-6 mpg less calculated.

I have a case number and contact rep and haven't called Torrance, CA to check since late fall. I will try to do that over the next couple of days.

Wayne, purely editorial: have a read through your opening post, pretending you're just a layman. Even though I'm starting to catch on, I've got to say it was heavy slogging to comprehend:

"local Carmax" No clue
"write up a ticket" D.O.
"Ok, took some numbers" D.O.
"actual ADN fcd" D.O. (to the max)
"That was that" Yeah... LOL
"You could EV forever" I actually grok that one, but...

Are we getting to esoteric? Just Friday grumbles ;)

I gather you're saying there's a disparity between in-dash mileage display and actual calculated mileage.

Hi Mendel:

___Part of being a CleanMPG'er I guess :)

Carmax is a nationwide Auto chain selling Chevrolet and Toyota vehicles.

Write up a Ticket so its recorded in the Toyota Data Base that there is a problem.

Tech and Service writer looked at the dash and wrote down the Trip A FCD at 490 miles and 53.9 mpg IIRC.

Actual Fuel Economy and Fuel Consumption Display Fuel Economy.

Welcome to the Friday morning/afternoon double speak reset :)

___Good Luck

___Wayne

I called and and left a message for my customer care agent along with case number last Friday. She called me back this morning and did not have any news. She documented my call and suggested that I call my dealer. I told her that I usually call my dealer and let them know of any updates. We find out about those on the net before the dealer hears about them.

25,000 miles and still an average 10% error. The tanks have ranged from 54 to 79 MPG on the trip meter. I have had my complaint in to the dealer, logged a report with Toyota Customer Care and have the same rep as msirach. No further contact and certainly no resolution forthcoming it seems. Maybe it's time to produce a little press or go to one of those consumer TV advocates. Or maybe some of those class action lawyers doing all the Toyota lawsuits are still hungry.

Wayne

You're right Wayne. I am getting impatient. Just Tweeted the following. I will see if Toyota is as attentive as GM is now to social media.

@Toyota @CleanMPG No fix yet for early 2010 Prius 10%+ FCD error??? Recent Prius are accurate. Unanswered claim since June 2009

Hi All,

After 4 tanks, my FCD averages 5.7% high (max 8%, min 3.2%). This car was purchased in mid Sept 2010. So, its not fixed with the newer cars. Its the same.

Hi Donee:

Thanks for the note and it is really too bad that Toyota is doing this. It still ticks my mom off and that is the last thing I wanted her to experience in her first Toyota and her first hybrid :(

Good Luck

Wayne

Mine , made in march 10, bot in May 10 over 10,000 miles reads about 2 mpg better than the pump (Car says 60.3 mpg avg, pump says 58.2).

If I recall correctly, there have been statements issued by Toyota's engineers indicating that a 5% percent discrepancy is "normal" - as in expected.

Obviously a 10% margin of error is far for acceptable even when you consider that Toyota already intended to have a 5% over-estimate.

With this said, I cannot say I experienced discrepancies anywhere close to 10%. If anything, its been an odd and rather unpredictable experience that I've already gotten used to. For instance:


The first couple of tanks were almost dead-on accurate, which mistakenly led me to believe that the problem had been fixed after the second production batch rolled off the lines. I was obviously very wrong on this one. (I almost never buy 1 production batches)
The remaining tanks have exhibited a 2-5% discrepancy on average for ambient temperatures above 10C (50F).
Winter time discrepancies usually exceed the 5% margin by a small margin especially when ambient temps are below freezing.
I have never, ever had a tank where the car's displayed FE was worse than the calculated FE at the pump. Then again, the Gen II Prius are pretty much the same, so nothing new here.


Lastly, my observations were performed since August 2009 with the exclusive use of Shell gas from the very same station and pump. ;)


Cheers;

MSantos

Our 2006 remains about 10% optimistic-4 mpg.
It will typically show 43 mpg-actual will be 38-39.
This has been for the entire 49,000 miles.
My wife and son make no hypermiling attempts in heavy city short trip driving.They got 22 mpg with the Prizm(Corolla) it replaced and 12-14 mpg with the Pilot it sorta' replaced.
The car will pretty easily deliver 55 mpg city with my very modest efforts, so there isn't anything wrong with the car.

Toyota obviously sets them up to display optimistic #'s.There isn't any "defect"; it is intentional.Most folks "believe" their display, and never consider actually calculating their true mpg. Heck, plenty of them couldn't easily eyeball calculate it without a calculator.They wouldn't be able to look at 8.1 gallons and 325 miles and know they were getting 40 mpg.
Charlie