Go Back   EcoModder Forum > EcoModding > Instrumentation
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-26-2009, 10:16 AM   #1 (permalink)
Engineering first
 
bwilson4web's Avatar
 
Join Date: Mar 2009
Location: Huntsville, AL
Posts: 792

14 i3-REx - '14 BMW i3-REx
Last 3: 45.67 mpg (US)

17 Prime Plus - '17 Toyota Prius Prime Plus
90 day: 58.25 mpg (US)
Thanks: 79
Thanked 196 Times in 126 Posts
Calibration of 2010 Prius MPG indicator

With 109 samples, manually collected from the PriusChat community, we now have enough data:


The blue 'dashed' line is the desired, calibrated values. If the indicated mileage were accurate, the data points would bound either side of the dashed blue line. As for the upper, outliers, they are still sparse but they seem to be around the trendline. This is not enough to 'bet the farm' but enough to not worry too much if extended.

The other interesting aspect is the double-humped, MPG distribution:


This closely agrees with the double-humped distribution from the small number of user mileage reports from the EPA database:


At this point, the ball is in Toyota's court. Absent some way to modify the software that calculates the indicated MPG, we just need to understand the problem and depending upon the requirements, there are these options:
  • use pump MPG for accuracy and indicated for relative MPG performance
  • use correction formula: actual = (.85 * indicated) + 5.3
  • use 3d party MPG indicator: scangauge, supermid or others (mpguino)

Feel free to share this with other Prius groups and thank the PriusChat community for their data contributions.

Bob Wilson

__________________
2019 Std. Range Plus Model 3 - 134 MPG3 || 2014 BMW i3-REx - 117 MPGe, 39 MPG
JuiceBox 40 Pro (240 VAC, 40 A), KHONS portable (120-240 VAC, 12-32 A)
Retired engineer, Huntsville, AL (five times AutoPilot saved.)

Last edited by bwilson4web; 08-26-2009 at 10:40 AM.. Reason: Correcting alternate MPG device lists.
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-26-2009, 10:23 AM   #2 (permalink)
dcb
needs more cowbell
 
dcb's Avatar
 
Join Date: Feb 2008
Location:
Posts: 5,038

pimp mobile - '81 suzuki gs 250 t
90 day: 96.29 mpg (US)

schnitzel - '01 Volkswagen Golf TDI
90 day: 53.56 mpg (US)
Thanks: 158
Thanked 267 Times in 210 Posts
FYI, Yoshi built the supermid specifically for the prius, and he and the folks testing it had the fuel consumption dialed in to within 1%, he also made some key contributions to the mpguino.
__________________
WINDMILLS DO NOT WORK THAT WAY!!!
  Reply With Quote
Old 08-26-2009, 10:40 AM   #3 (permalink)
Administrator
 
Daox's Avatar
 
Join Date: Dec 2007
Location: Germantown, WI
Posts: 11,175

CM400E - '81 Honda CM400E
90 day: 51.49 mpg (US)

Daox's Grey Prius - '04 Toyota Prius
Team Toyota
90 day: 49.53 mpg (US)

Daox's Insight - '00 Honda Insight
90 day: 64.33 mpg (US)

Swarthy - '14 Mitsubishi Mirage DE
Mitsubishi
90 day: 56.69 mpg (US)
Thanks: 2,475
Thanked 2,538 Times in 1,530 Posts
Hopefully Toyota will listen and correct this issue. I'd be horribly disappointed if my MFD was as far off as it is.
__________________
Current project: A better alternator delete
  Reply With Quote
Old 08-26-2009, 10:49 AM   #4 (permalink)
...beats walking...
 
Join Date: Jul 2009
Location: .
Posts: 6,190
Thanks: 179
Thanked 1,522 Times in 1,123 Posts
...does the Prius Owners Manual 'fine print' read: "...your milage may vary"?
  Reply With Quote
Old 08-26-2009, 01:53 PM   #5 (permalink)
Engineering first
 
bwilson4web's Avatar
 
Join Date: Mar 2009
Location: Huntsville, AL
Posts: 792

14 i3-REx - '14 BMW i3-REx
Last 3: 45.67 mpg (US)

17 Prime Plus - '17 Toyota Prius Prime Plus
90 day: 58.25 mpg (US)
Thanks: 79
Thanked 196 Times in 126 Posts
The NHW11/NHW20 had the bladder tank so no one could really check the MPG display without special instruments. If you had special instruments, you didn't really care because you'd use the more accurate source. Regardless, we're letting Toyota know about the problem. In fact, I'll open a case too, now that we know the characteristics of the problem.

One good thing is with the extensive software controlled systems, I suspect Toyota can easily fix this with a download. Considering we've only had our 2010 Prius for 90 days, I think this is remarkable progress.

Bob Wilson
__________________
2019 Std. Range Plus Model 3 - 134 MPG3 || 2014 BMW i3-REx - 117 MPGe, 39 MPG
JuiceBox 40 Pro (240 VAC, 40 A), KHONS portable (120-240 VAC, 12-32 A)
Retired engineer, Huntsville, AL (five times AutoPilot saved.)
  Reply With Quote
Old 08-27-2009, 05:05 PM   #6 (permalink)
Master EcoModder
 
Join Date: Sep 2008
Location: Texas
Posts: 632
Thanks: 0
Thanked 25 Times in 23 Posts
It looks like what may have happened is that the indicator was calibrated for ethanol-free gasoline (which has more energy per unit volume than ethanol gasoline). Hence the few points that were on or above the indicated line.
__________________
If America manages to eliminate obesity, we would save as much fuel as if every American were to stop driving for three days every year. To be slender like Tiffany Yep is to be a real hypermiler...

Allie Moore and I have a combined carbon footprint much smaller than that of one average American...
  Reply With Quote
Old 08-27-2009, 07:53 PM   #7 (permalink)
Engineering first
 
bwilson4web's Avatar
 
Join Date: Mar 2009
Location: Huntsville, AL
Posts: 792

14 i3-REx - '14 BMW i3-REx
Last 3: 45.67 mpg (US)

17 Prime Plus - '17 Toyota Prius Prime Plus
90 day: 58.25 mpg (US)
Thanks: 79
Thanked 196 Times in 126 Posts
Quote:
Originally Posted by NiHaoMike View Post
It looks like what may have happened is that the indicator was calibrated for ethanol-free gasoline (which has more energy per unit volume than ethanol gasoline). Hence the few points that were on or above the indicated line.
That is an interesting hypothesis.

Ken@Japan reports a Japanese engineer told him they designed it to read 5% high. I suspect Toyota may rethink that approach someday. Regardless the formula derived from the statistical data seems to be more accurate than a straight 5% bias.

Bob Wilson
__________________
2019 Std. Range Plus Model 3 - 134 MPG3 || 2014 BMW i3-REx - 117 MPGe, 39 MPG
JuiceBox 40 Pro (240 VAC, 40 A), KHONS portable (120-240 VAC, 12-32 A)
Retired engineer, Huntsville, AL (five times AutoPilot saved.)

Last edited by bwilson4web; 08-28-2009 at 04:25 PM..
  Reply With Quote
Old 05-06-2010, 04:51 PM   #8 (permalink)
EcoModding Lurker
 
Join Date: May 2010
Location: oklahoma
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
After the first 4 tanks on my Prius I am finding that it registers almost exactly 5% high on every tank so far. One on 10% ethanol (10% worse gas mileage) and the other 3 on real gas. I had a J.C. Penny fuel mileage indicator in 1975 that allowed me to calibrate it by putting in actual gallons at the pump. Surprised that Toyota hasn't been able to replicate a 35 year old technology?
  Reply With Quote
Old 05-06-2010, 09:38 PM   #9 (permalink)
Master EcoModder
 
NeilBlanchard's Avatar
 
Join Date: May 2008
Location: Maynard, MA Eaarth
Posts: 7,891

Mica Blue - '05 Scion xA RS 2.0
Team Toyota
90 day: 42.48 mpg (US)

Forest - '15 Nissan Leaf S
Team Nissan
90 day: 156.46 mpg (US)

Number 7 - '15 VW e-Golf SEL
TEAM VW AUDI Group
90 day: 155.81 mpg (US)
Thanks: 3,428
Thanked 2,914 Times in 1,827 Posts
E10 doesn't have a 10% drop in mileage. E85 might have a 10% drop in mileage; but not E10.

I agree, though about calibrating the stock FE indicator -- the ScanGuage II does it, and so could the factory unit.
__________________
Sincerely, Neil

http://neilblanchard.blogspot.com/
  Reply With Quote
Old 05-07-2010, 01:13 AM   #10 (permalink)
EcoModding Lurker
 
Join Date: May 2010
Location: oklahoma
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Mine do Every time. Three cars, all do the same. Many tanks... Same result.

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Project: Rebuilding an '01 Honda Insight as a nonhybrid Fabio Hybrids 158 01-12-2013 12:59 PM
Gen III 2010 Prius Matt Herring Hybrids 3 08-30-2010 04:04 AM
PBS takes the Hummer v Prius bait SVOboy Hybrids 51 05-19-2010 01:35 PM
2010 - Hybrid System Indicator fun bwilson4web Hybrids 2 08-03-2009 04:47 PM
2010 Prius unveiled: Cd 0.25, 50 mpg EPA combined, EV mode MetroMPG Hybrids 56 07-26-2009 04:48 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com