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The Pump and the Nav - Comparison
Thought I woould start a new thread for comparing MPG calculations from the fillup and the navigation system. This way we don't have to read through all the convo's in the other thread.
10/24/08 34.06 Pump / 35.8 Nav = 5.10% 11/5/08 34.04 Pump / 35.5 Nav = 4.29% 11/20/08 32.37 Pump / 33.4 Nav = 3.17% |
Re: The Pump and the Nav - Comparison
I'm glad I'm not the only one who likes to stir the pot every once in a while. Keeps things somewhat exciting around here.
By looking at your numbers, I'd have to say that your NAV readings are inaccurate by about 4% on the high side. Whether it be by the onboard computer or by a Scan gauge or any other device, the most accurate measure of what your vehicle gets is based on the following formula: Total miles driven / total gallons of gas added to vehicle = average mpg This formula eliminates the slight error caused by the differences in the level of fill for the tank. The more tanks you have in the data, the less that error becomes. There is no way any device can get a more accurate measure of the average fuel efficiency than that. I'm sure someone will be along shortly to tell me I am full of it.....they always are. |
Re: The Pump and the Nav - Comparison
Originally Posted by twolostminds
(Post 191797)
Thought I woould start a new thread for comparing MPG calculations from the fillup and the navigation system. This way we don't have to read through all the convo's in the other thread.
10/24/08 34.06 Pump / 35.8 Nav = 5.10% 11/5/08 34.04 Pump / 35.5 Nav = 4.29% 11/20/08 32.37 Pump / 33.4 Nav = 3.17% 9/2/08 46.659 Pumped / 46.4 Nav = -.5% 9/18/08 45.86 Pumped / 47.0 Nav = 2.5% 10/4/08 45.173 Pumped / 47.8 Nav = 5.8% 10/25/08 46.04 Pumped / 47.8 Nav = 3.9% 11/14/08 48.06 Pumped / 50.0 Nav = 4.0% These are all of my tanks 2-6 except the first because I reset the Nav after the dealership and the factory miles averages. My '09 FEHL MPG record is now logged in the data base at Clean MPG and anyone can view each tank average for more details. I keep my own log of the Nav and the SGII tank readings at fill-up. My FEHL has burned 88.364 gallons since the factory start-up and I had 3,974.1 miles on the permanent OD at my 6th Tank. This gives my '09 FWD FEHL a lifetime average of 44.974mpg. I purposely averaged all factory start-up and testing, transport operations running and dealer handling and prep into my Lifetime Average. GaryG |
Re: The Pump and the Nav - Comparison
Originally Posted by GaryG
(Post 191802)
You're going to find this interesting:
9/2/08 46.659 Pumped / 46.4 Nav = -.5% 9/18/08 45.86 Pumped / 47.0 Nav = 2.5% 10/4/08 45.173 Pumped / 47.8 Nav = 5.8% 10/25/08 46.04 Pumped / 47.8 Nav = 3.9% 11/14/08 48.06 Pumped / 50.0 Nav = 4.0% These are all of my tanks 2-6 except the first because I reset the Nav after the dealership and the factory miles averages. My '09 FEHL MPG record is now logged in the data base at Clean MPG and anyone can view each tank average for more details. I keep my own log of the Nav and the SGII tank readings at fill-up. My FEHL has burned 88.364 gallons since the factory start-up and I had 3,974.1 miles on the permanent OD at my 6th Tank. This gives my '09 FWD FEHL a lifetime average of 44.974mpg. I purposely averaged all factory start-up and testing, transport operations running and dealer handling and prep into my Lifetime Average. GaryG |
Re: The Pump and the Nav - Comparison
The ScanGauge does not take into account Fuel Trim.
The ScanGauge assumes you are using 100% gasoline. Maybe the on-board MPG meter is the same? I thought the on-board one would be 'smarter'. People who get lower numbers at the pump, are probably using 10% ethanol. 10% ethanol lowers my MPG by about 3.5% to 4%. On 10% ethanol my LTFT reads 3.5% most of the time. The SG always reads 3.5% to 4% higher. When I put E85 in my car ( yes, I do it sometimes, with no ill effects so far ) My MPG goes down 30%, and my LTFT goes to 28.5%. SG shows normal MPG ( mid thirties ) when reality is mid-twenties. Coincidence? I think NOT! My Nav MPG moves up and down a little with changes in ethanol, but not in the correct proportions, So I don't know what the heck it is doing or how it gets it's calc. P.S. Just for GaryG: I am POSITIVE the SG does not read the ethanol.... thus, at your MPG "Challenge" with Debbie's car, you got accurate results for what you WOULD have had on pure gas. The SG didn't know the car had E10. Next time, you could use E50 and get the same SG readings. Kinda good to know the fuel in the tank didn't skew participant's standings! |
Re: The Pump and the Nav - Comparison
Originally Posted by denverjay
(Post 191800)
I'm glad I'm not the only one who likes to stir the pot every once in a while. Keeps things somewhat exciting around here.
|
Re: The Pump and the Nav - Comparison
Originally Posted by denverjay
(Post 191800)
I'm glad I'm not the only one who likes to stir the pot every once in a while. Keeps things somewhat exciting around here.
By looking at your numbers, I'd have to say that your NAV readings are inaccurate by about 4% on the high side. Whether it be by the onboard computer or by a Scan gauge or any other device, the most accurate measure of what your vehicle gets is based on the following formula: Total miles driven / total gallons of gas added to vehicle = average mpg This formula eliminates the slight error caused by the differences in the level of fill for the tank. The more tanks you have in the data, the less that error becomes. There is no way any device can get a more accurate measure of the average fuel efficiency than that. I'm sure someone will be along shortly to tell me I am full of it.....they always are. 1. The error between the Nav & the Pump is not just on our Nav. 2. Average error % by compiling information from several vehicles. 3. What may be causing these errors. (GPSMan had a good theory about LTFT and Ethanol gas.) 4. Is there anything we can do to fix the Nav error or have this error fixed. I probably have more reasons for starting this thread but I need to go stir the pot...err I mean brew some coffee. |
Re: The Pump and the Nav - Comparison
Originally Posted by colchiro
(Post 191841)
I thought that was Billyk.:zip:
That said and respect to the previous post on scanguages: Using mathematics relative to energy content per volume and mixing ratios, one comes up percent decrease in energy per gallon compared to 100 percent gasoline.”with an energy content of 109,300 Btu per gallon for E10. This is approximately a 3.3 If it is all about BTU's -energy content---then how does one lose more than four times (15%) this in MPG when running E10?:confused: It can't be bad driving can it? My personal experience does not match this type of difference. Heck, running E30 (5 gallons of E85 in a 15 gallon tank) does not drop my MPG 45%. |
Re: The Pump and the Nav - Comparison
Originally Posted by twolostminds
(Post 191846)
Not quite sure how I'm stiring the pot with this thread. I opened it to fin out....
Sorry if you took my comment personally - it wasn't meant as a dig.:zip: |
Re: The Pump and the Nav - Comparison
Originally Posted by gpsman1
(Post 191839)
The ScanGauge does not take into account Fuel Trim.
The ScanGauge assumes you are using 100% gasoline. Maybe the on-board MPG meter is the same? I thought the on-board one would be 'smarter'. People who get lower numbers at the pump, are probably using 10% ethanol. 10% ethanol lowers my MPG by about 3.5% to 4%. On 10% ethanol my LTFT reads 3.5% most of the time. The SG always reads 3.5% to 4% higher. When I put E85 in my car ( yes, I do it sometimes, with no ill effects so far ) My MPG goes down 30%, and my LTFT goes to 28.5%. SG shows normal MPG ( mid thirties ) when reality is mid-twenties. Coincidence? I think NOT! My Nav MPG moves up and down a little with changes in ethanol, but not in the correct proportions, So I don't know what the heck it is doing or how it gets it's calc. P.S. Just for GaryG: I am POSITIVE the SG does not read the ethanol.... thus, at your MPG "Challenge" with Debbie's car, you got accurate results for what you WOULD have had on pure gas. The SG didn't know the car had E10. Next time, you could use E50 and get the same SG readings. Kinda good to know the fuel in the tank didn't skew participant's standings! During the MPG Challenge, Debbie had adjusted her SGII to read 7.5% lower than her Nav Sys. She had a real low tank fill and made the adjustment prior to the Challenge. The only effects of E10 was it lowered the mpg what we would have gotten on straight gas after the long term fuel trim was adjusted. Our '09 FEH/MMH has a new 190 pin powertrain control module (PCM) and I read the dealership scan tools had to be calibrated for the new PCM. I have a feeling this is why I'm seeing much higher mpg readings on the SGII. No big deal because I can adjust the SGII to read correctly. I was working on finding the percentage the Nav Sys was off, but thanks to Mike and this thread, a few more of us can put our heads together. Not sure the 11.1% adjustment to the SGII tank refill was enough though. Right now with 213 miles on this 7th tank, the SGII is reading 49.4mpg and the Nav Sys is reading 50.6mpg. If the nav sys is 4% high like we think, the SGII should be adjusted to read 48.5mpg. GaryG |
Re: The Pump and the Nav - Comparison
10/24/08 34.06 Pump / 35.8 Nav = 5.10%
11/5/08 34.04 Pump / 35.5 Nav = 4.29% 11/20/08 32.37 Pump / 33.4 Nav = 3.17% 12/4/2008 30.99 Pump / 32.6 Nav = 5.20% Creeping up on a 4.5% error rate. :( Also dont like the way the colder weather has been dropping our FE but I doubt Mother Nature will do anything about that. lol On the bright side, this morning on the 4.7 mile trip home from filling up the gas tank we got 43 MPG! |
Re: The Pump and the Nav - Comparison
Originally Posted by twolostminds
(Post 192778)
10/24/08 34.06 Pump / 35.8 Nav = 5.10%
11/5/08 34.04 Pump / 35.5 Nav = 4.29% 11/20/08 32.37 Pump / 33.4 Nav = 3.17% 12/4/2008 30.99 Pump / 32.6 Nav = 5.20% Creeping up on a 4.5% error rate. :( Also dont like the way the colder weather has been dropping our FE but I doubt Mother Nature will do anything about that. lol On the bright side, this morning on the 4.7 mile trip home from filling up the gas tank we got 43 MPG! 9/2/08 46.659 Pumped / 46.4 Nav = -.5% 9/18/08 45.86 Pumped / 47.0 Nav = 2.5% 10/4/08 45.173 Pumped / 47.8 Nav = 5.8% 10/25/08 46.04 Pumped / 47.8 Nav = 3.9% 11/14/08 48.06 Pumped / 50.0 Nav = 4.0% 12/4/08 48.815 Pumped / 51.8 Nav = 6.2% This brings my total miles to 4658.3 on my '09 FEH with 102.374 gallons burned from start-up at the Factory. This new tank puts my Lifetime MPG at 45.5mpg. As far as the Nav Sys Tank Average display, the 6 percentages above for me added to 22.9%, divided by 6 tanks = 3.816%. You had only 4 tanks to compare in a row and if you take my last 4 tanks, my average would be much higher also. We both need to continue monitoring the Nav Sys MPG readings for long term results for the group of '09 FEH owners with Nav. GaryG |
Re: The Pump and the Nav - Comparison
Just completed my 7th Tank on my '09 FEH and here are the best numbers yet. The Nav Sys had a Tank reading average of 54.1mpg which was 4.45% higher than E10 pumped of 13.552 gallons. This was on a 702 mile tank which gave me a 51.8mpg average using pumped gas calculations. My weather averaged 60 - 80F degrees which was I'm sure far better than the cold weather most are having up North right now. The wind was bad 75% of the time but this new RFS technique was awesome in city driving.
Here is my list of pumped gas VS the Nav Sys readings to date for only the '09 models to compare: 9/2/08 46.659 Pumped / 46.4 Nav = -.5% 9/18/08 45.86 Pumped / 47.0 Nav = 2.5% 10/4/08 45.173 Pumped / 47.8 Nav = 5.8% 10/25/08 46.04 Pumped / 47.8 Nav = 3.9% 11/14/08 48.06 Pumped / 50.0 Nav = 4.0% 12/4/08 48.815 Pumped / 51.8 Nav = 6.2% 12/18/08 51.80 Pumped / 54.1 Nav = 4.45% This brings my total miles to now to 5,360 on my '09 FEH with 115.926 gallons burned from start-up at the Factory. This new tank puts my Lifetime MPG at 46.236mpg. As far as the Nav Sys Tank Average display, the 7 percentages above for me added to 27.35%, divided by 7 tanks = 3.9%. So for me, the Nav Sys continues to read ~4% higher MPG than pumped gas. On this Tank before fill-up I had 10 MTE left with 702 miles on the trip OD. This is the third time my MTE read a maximum of 699 Miles To Empty after fill-up, so the '09 will never exceed that number like prior FEH/MMH models can. GaryG |
Re: The Pump and the Nav - Comparison
10/24/08 34.06 Pump / 35.8 Nav = 5.10%
11/5/08 34.04 Pump / 35.5 Nav = 4.29% 11/20/08 32.37 Pump / 33.4 Nav = 3.17% 12/4/2008 30.99 Pump / 32.6 Nav = 5.20% 12/15/2008 30.78 Pump / 31.9 Nav = 3.71% 5 tanks ~4.294% Error Rate So far tank 6 isn't looking to good with the NJ weather. 28 MPG on the Nav :( :( :( |
Re: The Pump and the Nav - Comparison
Gary- Maybe it is coincidence, but....
Your Nav is reading 3.9% high. E10 is supposed to lower MPG by 3.5% ( based on btu ). ( But is also supposed to lower emissions by 25% ) Just thinking out-loud... maybe the Nav doesn't know you have E10? So it is telling what you should have on plain gas? |
Re: The Pump and the Nav - Comparison
Originally Posted by gpsman1
(Post 193930)
Gary- Maybe it is coincidence, but....
Your Nav is reading 3.9% high. E10 is supposed to lower MPG by 3.5% ( based on btu ). ( But is also supposed to lower emissions by 25% ) Just thinking out-loud... maybe the Nav doesn't know you have E10? So it is telling what you should have on plain gas? As far as the Nav Sys reading 3.9% high, it does not compare to my SGII readings which are 3 times as high as the default settings compared to the Nav Sys. I had one SGII set at 11.8% lower and still got a Tank reading of 52.5mpg when pumped gas was at 51.8mpg. I've posted new photos today on Cleanmpg.com of my Nav reading and SGII readings and new adjustments for my ninth tank: http://www.cleanmpg.com/photos/showg.../500/ppuser/36 You can also see the maximum Miles To E the '09 will ever read in one photo. GaryG |
Re: The Pump and the Nav - Comparison
10/24/08 34.06 Pump / 35.8 Nav = 5.10%
11/5/08 34.04 Pump / 35.5 Nav = 4.29% 11/20/08 32.37 Pump / 33.4 Nav = 3.17% 12/4/2008 30.99 Pump / 32.6 Nav = 5.20% 12/15/2008 30.78 Pump / 31.9 Nav = 3.71% 12/28/2008 28.07 Pump / 29.0 Nav = 3.33% Those 20 deg mornings killed us last week. :( |
Re: The Pump and the Nav - Comparison
Hi Mike
That now puts your 6 tank averages for the Nav Sys percentage above pumped gas at 4.13%. My 7 tank averages is 3.9% so we are getting close to a 4% average that the '09 FEH/MMH Nav Sys reads higher than gas pumped. I think I would be using alot of DFSO in that cold weather of yours to increase MPG. I use it above 40mph as much as possible when I can't go EV. Just slowly accelerate and coast in "D" over and over. It is a P&G technique that's is good in any weather. A steady state speed in a vehicle that has an aggressive fuel cut like our '09 FEH is a waste of MPG and even worst in cold weather. GaryG |
Re: The Pump and the Nav - Comparison
The Society of Automotive Engineers' has a voluntary maximum speedometer error rate standard of +/- 4%. The NTSB has no manditory maximum error rate as far as I know. We should all check and see if our spedo's are off by the same amount.
I can't find the article but IIRC Toyota got sued over a 3.75% error rate and had to shell out $6 million or something like that to people who leased their cars due to overcharging for millage and artificially shortened warranties. After that Toyota "corrected" the software "error" and the speedo error rate dropped significantly. |
Re: The Pump and the Nav - Comparison
Originally Posted by twolostminds
(Post 194642)
The Society of Automotive Engineers' has a voluntary maximum speedometer error rate standard of +/- 4%. The NTSB has no manditory maximum error rate as far as I know. We should all check and see if our spedo's are off by the same amount.
I can't find the article but IIRC Toyota got sued over a 3.75% error rate and had to shell out $6 million or something like that to people who leased their cars due to overcharging for millage and artificially shortened warranties. After that Toyota "corrected" the software "error" and the speedo error rate dropped significantly. Maybe that lawsuit caused Ford to get their act together. GaryG |
Re: The Pump and the Nav - Comparison
Honda was sued over speedos and odos reading high.
Rather than put up a fight, they gave everyone 5% longer warranties on mileage. ( Insight Hybrid ) My 2005 FEH gives me EV at 39.9 MPH and under ( actual ) which looks like 42 MPH. |
Re: The Pump and the Nav - Comparison
Originally Posted by gpsman1
(Post 194673)
My 2005 FEH gives me EV at 39.9 MPH and under ( actual ) which looks like 42 MPH.
They are both the most efficient SUV on the planet. At 41mph the ICE will kick-in according to the speedometer. If your FEH waits till 42mph you have a special FEH like Willard dreams of. For years my '05 FEH will start the ICE at 41mph on any downhill so I keep it just under that to stay in EV with the brake in "D" or "L" for regen. The '09 FEH does the same and restarts at 41mph, but 41mph is 41mph and not 39mph reading 41mph like my '05. You and Willard can now start a new website called Greenhijacked.com and fight over how much alcohol you add to your gas! Happy New Year! GaryG |
Re: The Pump and the Nav - Comparison
As the self appointed :lightningGrand PooBah:lightning of this thread I request that it stay on topic and not be hijacked by petty bickering over the E word.
Failure to comply with the ^^above^^ MAY result in a flock of loose bowled canadian geese pooping on your FEH. :eek::umbrella: ...Thank you |
Re: The Pump and the Nav - Comparison
Just completed my 9th Tank on my '09 FEH and here are the best numbers yet. The Nav Sys had a Tank reading average of 55.6mpg which was 3.05% higher than E10 pumped of 13.453 gallons. This was on a 718.9 mile tank which gave me a 53.437mpg average using pumped gas calculations. My weather averaged 60 - 80F degrees with 35 - 60F today. The wind was bad 50% of the time but this new RFS technique is still awesome in city driving.
Here is my list of pumped gas VS the Nav Sys readings to date for only the '09 models to compare: 9/2/08 46.659 Pumped / 46.4 Nav = -.5% 9/18/08 45.86 Pumped / 47.0 Nav = 2.5% 10/4/08 45.173 Pumped / 47.8 Nav = 5.8% 10/25/08 46.04 Pumped / 47.8 Nav = 3.9% 11/14/08 48.06 Pumped / 50.0 Nav = 4.0% 12/4/08 48.815 Pumped / 51.8 Nav = 6.2% 12/18/08 51.80 Pumped / 54.1 Nav = 4.45% 1/22/09 53.437 Pumped / 55.6 Nav = 3.01% This brings my total miles now to 6078.9 on my '09 FEH with 129.379 gallons burned from start-up at the Factory. This new tank puts my Lifetime MPG at 46.985mpg. As far as the Nav Sys Tank Average display, the 8 percentages figures above for me added to 30.36%, divided by 8 tanks = 3.795%. So for me, the Nav Sys continues to read ~4% higher MPG than pumped gas. Notice I'm increasing the Nav sys mileage at a steady pace but pumped gas goes up and down. There is a pattern with the Tank fills being higher and lower with the percentages the Nav sys being off. On this Tank before fill-up, I had 13 MTE left with 718.9 miles on the trip OD. This is the forth time my MTE read a maximum of 699 Miles To Empty after fill-up, so again, the '09 will never exceed that number like prior FEH/MMH models can. Update on the SGII Tank percentage adjustments: Speed is adjusted to plus 1% which is not enough, but plus 2% is to much. This results in a Tank trip reading on both SGII's I have to 715 miles VS the 718.9 miles on my FEH Trip OD. One of my SGII's was set at 12.5% (which is getting crazy) and my Tank average came out at 53.8mpg with 13.2 gallons used. The other SGII was set at 12.9% and that tank average was 53.6mpg with 13.3 gallons used. That was pretty close to pumped gas at 53.437mpg with 13.453 gallons pumped. I changed the 12.5% setting to 13.3% and left the other SGII Tank refill setting at 12.9%. At any rate I'm getting real close to having the right SGII Tank average setting for the '09 FEH. Note, that after a reset of the SGII and the Nav sys Tanks, it takes awhile (miles) for the averages to compare to each other in real numbers. GaryG |
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