As soon as I got my 2007 vRS SE I noticed the average MPG figure was VERY high compared to the readings I'd been getting on my 2004 vRS. I reported it to the dealer and said I would monitor the situation.

Here's the relevant part of the letter I recently sent him:

I have already advised that the onboard computer was recording unfeasibly high MPG readings out of all believability compared to what I had seen and achieved with the previous car. I have now run two tanks of fuel through the car careful to use the same pump at the same petrol station and filling up to the same level each time, and can now report the following objective statistics:

~ Topped up at 24200 miles shortly after purchase

~ Topped up at 24642 miles – interval = 442.3 miles

~ ~ ~ Fuel put in = 39.48 litres = 8.677 gallons resulting in an actual 50.97 mpg

~ ~ ~ Computer reading = 62.5 mpg = 22.6% under-reading

~ Topped up at 25044 miles – interval = 401.1 miles

~ ~ ~ Fuel put in = 35.45 litres = 7.791 gallons resulting in an actual 51.48 mpg

~ ~ ~ Computer reading = 63.1 mpg = 22.6% under-reading – remarkably the same figure!

The actual mpg figures obtained are what I’d expect from experience for the sort of

driving involved. My old car was measured in detail up to 60000 miles as giving an

actual 50.1 mpg with the computer over between 0.6 mpg and 5.9 mpg averaging

3.0 mpg over – or approx 6% - nearly 4x as accurate as the present car! I request

that the computer is recalibrated to give a figure much closer to reality.

I've picked the car up today and they say:

A] There's nothing wrong with it

B] No fault codes are showing

C] The matter has been referred to Skoda UK who say that nothing can be done

Is [C] true? At present it's useless...

Is the odometer working correctly?

Mine is nearly always 10% optimistic...is it possible (with VAGCOM perhaps) to recalibrate it?

from reading this forum, it seems to me the later cars are the ones that are overly optimistic, my 53 plate is pretty accurate

Yes, it can be recalibrated using VAG-COM. Instructions are somewhere on here...

Both my 1.4 TDIs are 10% out also in both MPG and Speed, I have fitted the Micro Fuzion GPS Radar Detectors (Legal) which also show your exact Speed thus showing the car Speedometer is reading too slow, proven out when you pass the smiley roadside Speed displays. I think it's fairly general that all the VW, Audi and Skoda cars have lower reading Speedometers.

I wired the Micro Fuzion units up (with overide on/off switch) to come on when the ignition is switched 'on'.

DB.

Yes, it can be recalibrated using VAG-COM. Instructions are somewhere on here...

... and I've already tried finding them but failed hence my posting. Does anyone know where?

Is the odometer working correctly?

It's difficult to check without having a known distance to compare it to.

The speedo in the old car was reading slightly over as expected when checked against a GPS speedo (actual - reading):

30-32, 40-43, 50-54, 60-64, 70-75 - but that's a lot less than the 22.6% error on the MPG reading.

As an aside I do find it REALLY annoying that once I've posted a response I then can do another without waiting 30 seconds before hitting the "reply" button without getting : "The administrator has limited the number of new posts you can submit within a short time frame. Please wait 30 seconds before replying or posting a new topic. "

I think it's fairly general that all the VW, Audi and Skoda cars have lower reading Speedometers.

It's not just VAG cars - it's all cars.

Legally the speedo can read between 0 and 10% over - but not under. Hence manufacturers are going to set at 3-5% over. I think the only car Autocar have tested with a truly accurate speedometer was the Rolls Royce Phantom

Edited 18 September, 201015 yr by DRJ

Both my 1.4 TDIs are 10% out also in both MPG and Speed, I have fitted the Micro Fuzion GPS Radar Detectors (Legal) which also show your exact Speed thus showing the car Speedometer is reading too slow, proven out when you pass the smiley roadside Speed displays. I think it's fairly general that all the VW, Audi and Skoda cars have lower reading Speedometers.

I wired the Micro Fuzion units up (with overide on/off switch) to come on when the ignition is switched 'on'.

DB.

ECER39 is the regulation that controls speedometer compliance in Europe and states that...

1. speed(indicated) must never be lower than speed(true)

2. speed(indicated) must never be higher than 110% speed(true) + 4km/hr

It's difficult to check without having a known distance to compare it to.

The speedo in the old car was reading slightly over as expected when checked against a GPS speedo (actual - reading):

30-32, 40-43, 50-54, 60-64, 70-75 - but that's a lot less than the 22.6% error on the MPG reading.

As an aside I do find it REALLY annoying that once I've posted a response I then can do another without waiting 30 seconds before hitting the "reply" button without getting : "The administrator has limited the number of new posts you can submit within a short time frame. Please wait 30 seconds before replying or posting a new topic. "

What engine does this car have?

You do need to check the odometer. If this is out by 22% too, then you could have a bad speed sensor.

The DIN (distance impulse number) or the cluster tables could also have been changed but it wouldn't make sense as the readings are high.

If the indicated MPG is correct you should check for fuel leaks.

What engine does this car have?

You do need to check the odometer. If this is out by 22% too, then you could have a bad speed sensor.

The DIN (distance impulse number) or the cluster tables could also have been changed but it wouldn't make sense as the readings are high.

If the indicated MPG is correct you should check for fuel leaks.

Not sure what your question "What engine does this car have?" means - since all vRSs have the same engine.

By "indicated" I presume you mean the actual calculated reading not the display indicated one.

Around 50mpg is what I would have expected from 6 years of 2004vRS driving for the journeys undertaken.

Edited 18 September, 201015 yr by DRJ

The computer reading in my vRS SE is way over optimistic. I mentioned tis to my dealer who said the only thing they could do was change the unit.

I don't think the Fabia computer can be changed via VagCom.

The instructions here relate to an Octavia.

The computer reading in my vRS SE is way over optimistic. I mentioned tis to my dealer who said the only thing they could do was change the unit.

I don't think the Fabia computer can be changed via VagCom.

The instructions here relate to an Octavia.

Thanks - interesting that one model CAN be changed but another apparently can't...

Edited 18 September, 201015 yr by DRJ

My 2006 (BLT) vRS also has a desperately over-optimistic fuel computer - it too reckons on 65mpg when the calculated mpg is about 50mpg. I'm pretty sure this topic has come up before and somebody posted that the fuel computer reading could be 'trimmed' in some way, but only by a couple of percent either way.

I have a 53 plate fabia vrs and when I fill her up range says 420miles I get 400 ish before haveing to refil always seems to be almost spot on as I do like to have a quick drive now and then think my avg is 37mpg as my driveing is almost all heavy traffic town and very little motorway

My understanding (and it's not gospel, it's just the result of discussions with Skoda UK technicians when they did my dashpod swap, is that the later cars over-read because there is a software fault in the ECU that causes the car to incorrectly read the injector pulses in relation to the roadspeed.

The fuel usage is measured by counting injector pulses (very accurate) and the roadspeed and distance are picked up from the ABS sensors (in a vRS!). Somewhere in the ECU there is a fault that incorrectly links the two to provide an MPG figure. It is worth noting that cars that read in km/h and l/100km are very accurate in their readings.

The roadspeed indicated on the dashpod is not related to the MPG figure at all, but is calculated straight from the ABS pulses and the calculation that performs this is in two parts - it reads one one scale up to 90mph and another scale beyond 90mph.

This could be an interesting project for Ben at Shark Performance I reckon. You could monitor your fuel economy for a month or so, say, then have him reset the calculation accordingly. I feel a PM coming on!

My understanding (and it's not gospel, it's just the result of discussions with Skoda UK technicians when they did my dashpod swap, is that the later cars over-read because there is a software fault in the ECU that causes the car to incorrectly read the injector pulses in relation to the roadspeed.

The fuel usage is measured by counting injector pulses (very accurate) and the roadspeed and distance are picked up from the ABS sensors (in a vRS!). Somewhere in the ECU there is a fault that incorrectly links the two to provide an MPG figure. It is worth noting that cars that read in km/h and l/100km are very accurate in their readings.

The roadspeed indicated on the dashpod is not related to the MPG figure at all, but is calculated straight from the ABS pulses and the calculation that performs this is in two parts - it reads one one scale up to 90mph and another scale beyond 90mph.

This could be an interesting project for Ben at Shark Performance I reckon. You could monitor your fuel economy for a month or so, say, then have him reset the calculation accordingly. I feel a PM coming on!

Thanks for the detailed response. It does seem odd that it appears nothing can be adjusted on a Fabia but it can on an Octavia - and it seems an obvious aspect where adjustment might be required...

Over 24% optimistic on today's top-up...

Thanks for the detailed response. It does seem odd that it appears nothing can be adjusted on a Fabia but it can on an Octavia - and it seems an obvious aspect where adjustment might be required...

Hi, I have a diferent problem on the same mpg gauge in that mine always stops at 43.2 mpg regardless if it is on the motorway or local. When you switch it on the next time the same reading is their, if you clear it and start again it stops at 43.2mpg. Any ideas please?

John.

The instructions linked above for the Octavia also work for the Fabia, at least they did for my 51 plate SDI which is now 99% spot on once I knocked 10% off the reading.

HTH

The instructions linked above for the Octavia also work for the Fabia, at least they did for my 51 plate SDI which is now 99% spot on once I knocked 10% off the reading.

HTH

Hi,

On my MY06 Fabia vRS I open controller 17 then adaptation 10 and scroll up to 3 and there is nothing there. I can see a few things in the controller (mainly mileage and service reminders) but nothing to let me adjust the fuel computer.

These instructions work fine on the Audi though, so I think it's just a case of the clusters being different on different cars. The SDI has it, the vRS doesn't. :(