...does that mean the mileometer is also over reading by approx 10% too? :eek:

My 70k Fabia has now been reduced to 63k then? :confused:

hmmmm, i wondered that.

hmmmm, i wondered that.

There must be a smidging of positivity in this world full of negativity ...somewhere, somehow, sometime, surely, please?

I can really feel that someone is going to come along and pee all over me chips some time soon. :rotz:

Apparently "Speedos in modern mass-produced "type" approved cars are allowed to over read by 10% plus 2.5MPH. " They are not allowed to read under.

...does that mean the mileometer is also over reading by approx 10% too? :eek:

My 70k Fabia has now been reduced to 63k then? :confused:

Yes it does. It also means that using the trip mileage and brim tank to give MPG is out by the same percentage. However, modern speedometers usually only over read by 2%. The accuracy also alters as your tyres wear.

If you get to a steady speed (NSL for example) reset the average MPH readout and compare it too a satnav speedo (as soon as a reading comes up on the trip computer), they seem to be the same, so on that I would say the odometer is correct, unless my satnav is wrong.

On my Fabia its ~10% out, would this be something they changed during the course of production?

Yes it does. It also means that using the trip mileage and brim tank to give MPG is out by the same percentage. However, modern speedometers usually only over read by 2%. The accuracy also alters as your tyres wear.

Well mine appears to be approx 10% out according to Mr T. Tom

77 shown = a true 70 according to him, and blast on an unrestricted section of Autobahn 2 years ago showed similar...just over 130 shown was a dsappointing and miserably sluggish 120 true. :(

I'm going to test this out anyway.

I'll set the Tom for a destination approx 10 miles away, reset the trip and drive it, and see what the trip says against the mileage shown to complete the journey at the start on the Tom', when I've " Reached my destination"

Does that make sense...ish, or am I the only one who knows what I'm wittering on about?

i've always found the TomTom mileage readouts match perfectly to what my car is telling me i have driven

Yes it does. It also means that using the trip mileage and brim tank to give MPG is out by the same percentage. However, modern speedometers usually only over read by 2%. The accuracy also alters as your tyres wear.

My octavia would overread by 5mph at motorway speeds - 7% or thereabouts, and the trip computer was out by a similar margin on fuel consumption.

The Odometer was accurate enough though.

My Bravo's speedo is more accurate with about 2-3mpg error at 70 though the fuel computer seems to be more random with between 5-10% depending on the tank full.

i've always found the TomTom mileage readouts match perfectly to what my car is telling me i have driven

Is my test going to end in tears then?

In the name of being a boring old fart, I'll test and report back.

Works Mk4 Mondeo is exactly 4mph out at all speeds against GPS and a calibrated speed trap.

Interesting theory, however even if this is correct I would imagine the reasoning would be for servicing, expecially the cam belt.

My octavia would overread by 5mph at motorway speeds - 7% or thereabouts...

My Octavia also over-reads by about 7%. Mine is a rough figure worked out by timing myself using the 100m markers on the side of the motorway & comparing it against my speedo reading. I didn't think to check the odometer.

I guess that means I also now have a top speed of over 156mph without any mod's or mapping! ;-)

Edited 23 September, 200916 yr by The Ors
Top Speed realisation