How accurate is the Running MPG readout on your MFD - PASSAT

[ciscodilla]

My previous vehicle was a 2011 MK6 Manual TDI. MPG was absolutely unbelievable. I put nearly 30,000 miles on the vehicle in less than 12 months. One tank I achieved nearly 55 MPG with an astounding 805 Miles covered. That came with a whole lot of middle fingers too I must admit.

What was also a pleasant surprise was how accurate the MPG on the MFD display was on on the Jetta. The readout usually came within .5 and 1.5 MPG and always on the positive side.

Now with the new Passat with my first fill-up I find that the MFD MPG readout is off by over +3MPG.

I hand calculated all my fill ups and track them religiously. I fill up to the exact same level and try my best to avoid to much foaming.

Jetta 2011 TDI (Retired)
http://www.fuelly.com/driver/ciscodilla/jetta

Passat 2012 TDI (Current)
http://www.fuelly.com/driver/ciscodilla/passat

Question is will it adjust over time or is there something I can do to hone in the accuracy of the MFD MPG readout.

[cheapa55TDI]

Mine is off as well. It was off since day one but now that I have larger wheels, i don't rely on the MFD much except I do subtract 2mpg from the MFD to see what my expected true avg mpg is with fuelly calculations. I drive mainly hwy and I can "only" get about 42mpg.

http://www.fuelly.com/driver/cheapa55tdi/passat

[mtbsteve]

I checked mine by hand as well and noticed 2-3 mpg off on my first few tanks. One example I remember was showing 42 and it was really about 39.5. Most cars I have owned have been off by 1-2 mpgs but it is still a helpful tool to keep my driving style in check. I do have a receipt from each fill up and I write the mileage down on each so one of these days I will fill out a spread sheet or Fuelly.

[MasVW11]

My previous vehicle was a 2011 MK6 Manual TDI. MPG was absolutely unbelievable. I put nearly 30,000 miles on the vehicle in less than 12 months. One tank I achieved nearly 55 MPG with an astounding 805 Miles covered. That came with a whole lot of middle fingers too I must admit.

What was also a pleasant surprise was how accurate the MPG on the MFD display was on on the Jetta. The readout usually came within .5 and 1.5 MPG and always on the positive side.

Now with the new Passat with my first fill-up I find that the MFD MPG readout is off by over +3MPG.

I hand calculated all my fill ups and track them religiously. I fill up to the exact same level and try my best to avoid to much foaming.

Jetta 2011 TDI (Retired)
http://www.fuelly.com/driver/ciscodilla/jetta

Passat 2012 TDI (Current)
http://www.fuelly.com/driver/ciscodilla/passat

Question is will it adjust over time or is there something I can do to hone in the accuracy of the MFD MPG readout.

my mfd has been reading 2-3 mpg higher than what I get when i divide odometer by gallons put in tank.

[Andy@Ross-Tech.com]

Mine has been about 5% optimistic on average. I tweaked it to 105% with VCDS about halfway through my current tank and plan to fill up today. I try to post the MFA reading in the notes of every Fuelly fillup:

http://www.fuelly.com/driver/wolfsburgde/passat

[ciscodilla]

If your readout is optimistic by 5% wouldnt you want to tweak it down to 95% as opposed to increasing it. Ive never used VCDS nor do I own a VAG cable. But I am very interesting in learning.
So mine is optimistic by 6.845%.

Actual = 42.39 MPG
MFD = 45.5 MPG

42.39/45.5 = .9316 Discrepancy

So I assume the edit in VCDS would be .9316.

I will probably run a few more tanks to get a refined average.

[kromicacid]

My car tells me im an average of .87 MPG high...

Look at colum P. Line 1 is Average of that column, and below is each fill
https://docs.google.com/spreadsheet/...kJta3pNczRyOUE

I just changed my settings to adjust for difference at 102% to see what the difference will be...

[B7PassatSE]

My MFD reads +3.4 MPG, on average, over actual MPG at fillup. I track it on spreadsheets and will start adding the MFD readout to my fuelly results.

[xjdaddy]

Mine averaged about 2-4 mpg optimistic so I changed to 105% and now 2 tanks in a row it has been 2-4 mpg pessimistic. I will probably adjust to around 102% next fill up to see if that is a nice happy medium.

[Andy@Ross-Tech.com]

Mine has been about 5% optimistic on average. I tweaked it to 105% with VCDS about halfway through my current tank and plan to fill up today. I try to post the MFA reading in the notes of every Fuelly fillup:

http://www.fuelly.com/driver/wolfsburgde/passat

BTW, on that fillup, I got 37.6 mpg compared to MFA of 34.3 so it may have overshot. I'll fill up today with some nice highway miles on the current tank. Showed 50.9 mpg average when I pulled into work this morning.

[Andy@Ross-Tech.com]

50.8 per MFA, 50.8 per fuelly on the last fillup. 105% seems to have done the trick so far.

[ciscodilla]

Nothing really changed on the second tank...I pumped 16.193 Gallons in the tank (all the way to the neck) and had traveled 727 miles. That calculates to 44.90 MPG Actual. The MFD read a running average of 47.8.
That is a discrepancy of about 3 MPG which is more that I care to accept. Id like to get it close to + or - 1 MPG ideally.

If I had access to a VAG cable what steps will I need to take to update the MFD MPG readout?
It looks that I am between 6% - 7% off.

Thanks for your help...

[Andy@Ross-Tech.com]

Use VCDS to go into 17-Instruments->Adaptation->"Display correction of consumption and operating range", and put in a new value of 105% (or 106 or 107 in your case). Test and Save.

[ciscodilla]

Use VCDS to go into 17-Instruments->Adaptation->"Display correction of consumption and operating range", and put in a new value of 105% (or 106 or 107 in your case). Test and Save.

Thanks Andy, I got hold of a Ross Tech Cable and made the changes suggested (106%). Hopefully that will do the trick. While I was in there I made a few adiitional changes which include the Rain Sensor Wipers + Auto Window Close on Rain sense. Ill report back on next fuel up.

I was beating my head trying to get the Comfort Window and sunroof closure via the key fob... I managed to get the Sunroof to work but not the Windows.

Any one have any ideas?

On a side note while performing an Auto Scan I recieved 2 fault codes. Are these normal?

2 Faults Found:
18648 - NOx Sensor 1 Bank 1
P2201 00 [096] - Implausible Signal
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 01100000
Fault Priority: 0
Fault Frequency: 21
Reset counter: 32
Mileage: 0 km
Date: 2000.00.00
Time: 00:00:00

5523 - Engine Start Blocked by Immobilizer
P1570 00 [032] - -
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 01100000
Fault Priority: 0
Fault Frequency: 21
Reset counter: 32
Mileage: 0 km
Date: 2000.00.00
Time: 00:00:00

[ciscodilla]

Im 2 tanks in using "105" and it seemed to have done the trick. My last tank the MFI was .16 MPG Pessimistic.

Im dialed in now.

[jetsfanindenver]

I a noobie here. What i wonder is how do you guys tell that the MFD is off by a real mileage. I get trip distance and i reset the trip setting at the bottom right corner of my speedometer.

I reset this on every fill up so I am able to tell what my mileage was for when i fill the tank up again.

But i don't know if there is a better way ?

[Andy@Ross-Tech.com]

50.8 per MFA, 50.8 per fuelly on the last fillup. 105% seems to have done the trick so far.

Bah! I thought I'd nailed it but the next tank (which was 95% around town) showed 32.8 on MFA vs 31.5 pen and paper, a difference of 4%. I'll keep monitoring.

[darrelld]

Bah! I thought I'd nailed it but the next tank (which was 95% around town) showed 32.8 on MFA vs 31.5 pen and paper, a difference of 4%. I'll keep monitoring.

I wonder how much of the MFD error is related to the tank fill inconsistency? I have yet to find a consistent way to reach full. I fill at the same pump using the same technique (fill at the lowest notch and finish with one bump) sometimes the gauge reads full other times it reads 7/8.

Short of running the fuel out of the neck each time I believe ambient air temps make a difference.

[Andy@Ross-Tech.com]

I fill til I can physically see non-foamy fuel every time and have pumped from the same pump at the same station for every fill of the car's life (both sides of the pump though):



P.S. PA's diesel is pretty.

[hawleyrw]

Using VCDS - I'm having trouble changing this area.
I always get an error - something about formatting. Says should be 123/12345/123 format or something like that.

Says initial value is 100%, and has the place for new value - I'm plugging in 110 and clicking Do It, thats when the error occurs.

Not sure what I"m doing wrong, any ideas?

I'm using VCDS with uCan cable - I've made several other changes without issue.

I'll keep trying.

[ixlr08]

I wonder how much of the MFD error is related to the tank fill inconsistency?

I wonder how much MFD error might be due to filter regens, fuel use that is not factored into the MFD calculation.

[MUG318]

I wonder how much of the MFD error is related to the tank fill inconsistency? I have yet to find a consistent way to reach full. I fill at the same pump using the same technique (fill at the lowest notch and finish with one bump) sometimes the gauge reads full other times it reads 7/8.

Short of running the fuel out of the neck each time I believe ambient air temps make a difference.

I have read a bit on this and the temp of the fuel cannot increase that much over what it is in the holding tank at the filling station during the time you are filling up the tank.

[B7PassatSE]

I wonder how much MFD error might be due to filter regens, fuel use that is not factored into the MFD calculation.

I'd agree with you if people like me with the 2.5 weren't having such varying readings as well. makes me want to

Edit: Here's the breakdown of my last few fillups (2.5 SE, same pumps and same time of day within 1 hour)

Actual - MFD - Difference
29.3 - 31.3 - 2
27.8 - 31 - 3.2
32.6 - 33.6 - 1
28.7 - 31.9 - 3.2
28.1 - 31.1 - 3
28.8 - 31.5 - 2.7
28.1 - 31.6 - 3.5

Average MFD Off 2.657142857

[5potguy]

Hi All, I'm the kinda guy that likes everything spot On.. but I've only ever used the MFD as a
G U I D E, small percentages off either + or - never really bother me. The Fill Up/Log Mileage system is the only (to my mind) real MPG reading that matters

[B7PassatSE]

Hi All, I'm the kinda guy that likes everything spot On.. but I've only ever used the MFD as a
G U I D E, small percentages off either + or - never really bother me. The Fill Up/Log Mileage system is the only (to my mind) real MPG reading that matters

I agree completely that's why I use Fuelly and an Excel spreadsheet at home to track my true MPGs and other tidbits but you'd think they'd at least be close to the real thing. 1% of I can see but 2-3+% is unacceptable I think considering the computers can track fuel flow, pressure, throttle position, etc.

[5potguy]

I agree completely that's why I use Fuelly and an Excel spreadsheet at home to track my true MPGs and other tidbits but you'd think they'd at least be close to the real thing. 1% of I can see but 2-3+% is unacceptable I think considering the computers can track fuel flow, pressure, throttle position, etc.

First I reckon that because Fuel stations are so easily found, spot on readings or very near is not crucial. Secondly, as the vehicle is either accelerating/braking the info is lagging behind by default. My Azera regularly showed silly mileage, maybe 8 or 9mpg after a 10mile freeway run. Hyundai told me that it could take 50miles to register correctly! or you can reset when you get on the freeway to get a more up to date reading. In any event the vehicle computer is probably calibrated as where some older *speedos"" to be shall we say for the benefit of "eyes & wow"" rather than truism.. * A certain UK Chrysler actually showed 60MPH when in reality it was calibrated at 54-55mph.......

[ixlr08]

As has been discussed, these cars show MPH lower than actual, and I am finding the indicated miles traveled is less for a given trip than my other 3 cars. Before I worry too much about the MFD showing correct MPG's, is there any way to get the actual miles traveled to be correct so I have a good starting point to calculate MPG's? I thought I had seen a procedure, but I have spent hrs searching Vortex and TDIclub forums and I can't find anything on it, only the MPG readout correction.

Thanks,

[ColoradoDriver]

As has been discussed, these cars show MPH lower than actual, and I am finding the indicated miles traveled is less for a given trip than my other 3 cars. Before I worry too much about the MFD showing correct MPG's, is there any way to get the actual miles traveled to be correct so I have a good starting point to calculate MPG's? I thought I had seen a procedure, but I have spent hrs searching Vortex and TDIclub forums and I can't find anything on it, only the MPG readout correction.

Thanks,

Yes you can correct both the odometer and digital speed display to be much more accurate:

[Select]
[17-Instruments]
[Coding - 07]
[Long Coding Helper]
Click on each of the Byte numbers in row 3) and you'll see the selectable options below.
In this case, Byte 0 contains the "Distance Impulse Number".

2012 Passats are set at "3" by default. If you change that number to "2" it will improve accuracy when using stock wheels/tires.

In my case, using 225/50R18 tires, I changed the value to "1" and got the results I wanted.

That fixed both the odometer and digital speed display. The analog speedo is still a bit optimistic, but I usually use the digital speedo anyway.

[ixlr08]

Yes you can correct both the odometer and digital speed display to be much more accurate:

[Select]
[17-Instruments]
[Coding - 07]
[Long Coding Helper]
Click on each of the Byte numbers in row 3) and you'll see the selectable options below.
In this case, Byte 0 contains the "Distance Impulse Number".

2012 Passats are set at "3" by default. If you change that number to "2" it will improve accuracy when using stock wheels/tires.

In my case, using 225/50R18 tires, I changed the value to "1" and got the results I wanted.

That fixed both the odometer and digital speed display. The analog speedo is still a bit optimistic, but I usually use the digital speedo anyway.

Thank you... I finally got some time today to make this change, it puts the digital speed and odo much closer to the speed/distance the car is actually traveling. The analog speedo seems to be closer as well. I am going to try changing it to "1" but I suspect that is going to push it too far in the other direction as I am running the stock tires.

[ColoradoDriver]

Thank you... I finally got some time today to make this change, it puts the digital speed and odo much closer to the speed/distance the car is actually traveling. The analog speedo seems to be closer as well. I am going to try changing it to "1" but I suspect that is going to push it too far in the other direction as I am running the stock tires.

Changing to "1" will be too far for stock size tires. It is about perfect for taller 225/50R18.

[irishpride]

added to diy

[Andy@Ross-Tech.com]

Today's fillup (still with the 105% Adaptation tweak) is almost spot on. 37.7 MPG vs 37.8 on the MFI

http://www.fuelly.com/driver/wolfsburgde/passat

[ixlr08]

My first full tank fillup came to a calculated 56.0mpg, MFI showed 56.6mpg, no adaption done to the MPG settings, that is close enough for me. But, I did do an adaption change to the distance traveled/mph setting which brought my distance traveled and my mph closer to actual which may have brought my MFI for MPG closer to calculated.

[passsattdi]

Bah! I thought I'd nailed it but the next tank (which was 95% around town) showed 32.8 on MFA vs 31.5 pen and paper, a difference of 4%. I'll keep monitoring.

Andy,
Mine is not consistent. I too fill until you see it. Tells me 53.3 and sometimes calculates at just under 51 to 51.4.
I seem to have a difference in the mileage. It seems to be off by about 1 mile+ on 30. In other words I am reading 30 and going 31. Calculating, it seems to make my readings much closer. Wish I had the M6 in the SEL. Probably would get 55+ MPG.

[passsattdi]

I fill til I can physically see non-foamy fuel every time and have pumped from the same pump at the same station for every fill of the car's life (both sides of the pump though):



P.S. PA's diesel is pretty.

Looks like your station is filling you up with off road desiel. Off road is green, heating oil red and low sulfer should be clear.