Trip Computer Accuracy?

GrumpyOldMan · Jan 16, 2007

Had an Ibiza FR TDi for nearly three months now and love it. Its great to drive and according to the trip computer I get around 58 MPG.

I've measured the fuel consumption myself and find that the trip computer is about 20% high and that I'm actually getting about 48 MPG.

The dealer tells me that both the economy I'm getting and the trip computer being so far off are completely normal.

Looking at other threads it does sound like 48 MPG is about right, but I would be intereted if anyone has actaully measured much better than this. Also if you 've also found the trip computer is way off i'd be interested as I'm currently arguing with Seat trying to get it fixed. They agree its pants, but don't know how to fix it

BTW - I wasn't sure whether to post this on the TDi or the Ibiza forum, but I expect the same system is used on all TDi's that have a trip computer, so even if you have a TDi Leon say, I'd be interested in your thoughts.

UncleFester · Jan 16, 2007

Hmm i rather thought mine was accuratish - current average on both says 32mpg which i think is about right for what i do with it.

craig-pd130 · Jan 17, 2007

48mpg is good for normal mixed driving.

The computers vary in accuracy. Mine is 5% optimistic. Your is very optimistic, but I don't think it's adjustable / fixable. Just work out HOW inaccurate it is, then you've got an easy calculation to get your true MPG.

Deleted member 5241 · Jan 17, 2007

Mine lies by about 2 - 3 mpg low

muddyboots · Jan 17, 2007

20% does seem a lot further out than normal, but like Craig says I don't think anything could be done to fix it.

Unless you have a cheap resistor-in-a-box tuning module that fits inline with the fuel temp sensor to fool the ECU, that will make it hugely optimistic.

muddyboots · Jan 17, 2007

By the way, I assume when you're quoting 58mpg, you're reading the trip average or the long-term average display - not the instantaneous ?

toledoChris · Jan 17, 2007

Strangely my 06 fabia VRS has exactly the same problem, ive put it down to them being Euro IV complient. Seems to be over reading by roughly the same amount aswell - ive actually managed to get mine to record over 90mpg on a 90 mile trip!

daveyonthemove · Jan 17, 2007

Mine is pretty accurate. must be unlucky as some others have said the same.

GrumpyOldMan · Jan 17, 2007

muddyboots said:
By the way, I assume when you're quoting 58mpg, you're reading the trip average or the long-term average display - not the instantaneous ?

Yep, just before I fill up I read the long term avg. mileage and mpg then reset it after the fill-up.

I'm currently arguing with Seat as to how to get it fixed. Its clearly not the end of the world that it gives a completely wrong reading, but thats not the point. I paid for it and I expect it to work with a reasonable tolerance. Seat technical agree it should be better but can't give the dealer any advice on how to fix it.

The car's 3 months old, and its been blessed with all the common niggles - rattly gear stick in neutral, condensation in the headlamps and a slight stutter that is getting worse. I haven't moaned about the stutter yet, but all the other niggles the dealer just says 'wait' - the car needs to settle down!

Strange though it may seem to Seat and their dealers, I want to enjoy the car while its new.

Seat and their dealers really are a pain to deal with. I think one of the problems is down to them not having any product development in this country, so they seem at a loss as to how to resolve anything but the most basic problems, unless they have had a service bulletin from Seat or VAG.

jonjay · Jan 18, 2007

Get your money back! hehe!

Cant they replace the computer or is that not possible? How sure are you that your readings are accurate? How did you figure it out?

sssstew · Jan 18, 2007

muddyboots said:
20% does seem a lot further out than normal, but like Craig says I don't think anything could be done to fix it.

Unless you have a cheap resistor-in-a-box tuning module that fits inline with the fuel temp sensor to fool the ECU, that will make it hugely optimistic.

yep agreed. mines is fairly constantly 2-4 mpg too optimistic.

devonutopia · Jan 18, 2007

Mine's pretty accurate. (fabia "vRS") Long term average is currently sat at about 51mpg (was on 50.7 last night) and I do get roughly 500 miles to a 45 litre tank, which equates to 10 gallons, and 50mpg.

AndyC567 · Jan 24, 2007

After reading this, checked mine...

Works out only about 2 to 3 mpg high, not to bad..

Still a fairly good indicator though.

skullmunki · Jan 24, 2007

sorry to go off topic slightly, but is the computer supposed to revert to the outside temp whenever you fire up the engine? i'll get home with the clock on, and when i go out again its showing the temp (not caught the stalk either)!

its no big deal, was just wondering!

muddyboots · Jan 24, 2007

It will do if the temp is below a certain level (4º I think) to warn you off the possibility of ice.

FR*Man1984 · Jan 24, 2007

yeah muddy's right here, mine did exactly that this morning and i didn't press anything. also it should sound a slight chime to warn you and flash once in motion! a handy iccle feature

skullmunki · Jan 24, 2007

aye, its been 2 - 3 deg while its been doin it. Nifty feature i suppose, although the fact that i have to defrost my windscreen kind of gives me an idea it might be icy!

Thanks for the info chaps!

oldman · Jan 25, 2007

i'm quite mixed with driving and get normally about 45-47 on a 35min 28 mile trip twice a day, bit of slow A and bit of blasting A in a tdi 150 with avg of about 500-520 from a full tank every 7-10days so i'm very happy

muddyboots · Jan 26, 2007

oldman said:
i'm quite mixed with driving and get normally about 45-47 on a 35min 28 mile trip twice a day, bit of slow A and bit of blasting A in a tdi 150 with avg of about 500-520 from a full tank every 7-10days so i'm very happy

So how accurate is the trip computer ?

Pugster · Jan 26, 2007

I don't know if it applies to the Ibiza, but I know you can adjust the MFA accuracy using VAG-COM on a MKV Golf.

See here:

http://deviantspeed.com/jetta-gti-rabbit-ecu-recoding-vag-com

And scroll down to the bottom of the page

Trip Computer Accuracy?

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