Is it me or my speedo is weird...

[The_Hawk]

I was on the understanding that speedo readings were taken from the gearbox not the rim/tyre? So therefore would tyre wear be irelevant to speed calculations? Just throwing it out there..

Yes in most cases it's taken from the gearbox output shaft or something similar and your sort of right, at a given "speed" the wheel will always be turning at the same RPM. What makes a difference is the size of a wheel.

To exaggerate it completely, if a wheel turns 100 times a minutes and it's 1 meter round the outside of the wheel, the car will travel 100 meters in 1 minute. If you put a larger wheel on that is 2 meters round the outside, it is still connected to the same hub that will still turn it round 100 times, but this time the car will travel 200 meters.

Considering how many rpm's the wheels actually do a few millimeters wear times a few thousands revolutions per minute can add up to a couple of km/h hour difference.

[broady69]

The thing is, any mass produced car is going to have variations.

They would have setup a speedo and calibrated it during development stage and through time, speedo's will have minute differences from car to car.

Another reason the NEW VW speedo's are a little more inacurate than other cars is because they tried to be more modern with a speedo that changes speeds 3 times.

From 0 - 100 it's calibrated to read in multiples for 10km/h
From 100 - 180 " " " 20km/h segments
From 180 - 300 " " " 30km/h segments

The idea is nice but leaves more room for error than the Mk1 which just used to spin through the gearbox and turn the needle, now everything's going digital.

[The_Hawk]

Being digital you would think it would be easier to set the output level, even for different size wheels/tyres etc etc.

I'm sure there is MORE than enough testing in post production to fix something as simple as a speed reading which is run through the ECU anyway.

[datracer99]

Except tyre wear will result in more wheel revolutions for a given speed - meaning your speedo will read even faster relevant to the actual speed - and probably outside the 10% allowance under ADRs. I can't see any valid reason why VW don't make the speedo (more) accurate in the first place - most other makes do.

SS

Check out the review in Wheels of the Polo GTI vs Fiesta XR4 etc. Only one (Colt) was with 2km/hr.
All of the others, including the Polo, were out by about 8km/h at an indicated 100.
I'm sure it's to cover the maker against any law suits from people caught speeding, but it's damned annoying.
My GTI is out by a constant 5km/hr, so I pretty much only look at my GPS readout for my speed now.
To be out by a consistent 5kmh/hr when the speedo increments change (as noted above by broady69) means that it was built in that way through the electronics, it's not just through variances in the build from one car to another. If it was random you would get say 3kmh variance at 60, 5km variance at 100 and so on.

[jb747]

It's intentional. There's been a lot of discussion about this on the US forums. Given that Victoria gives you virtually no leeway before they hit you with a speeding fine, having the speedo intentionally inaccurate is at best Irish, and more likely hideous incompetence.

I've had 6 Toyotas, and all but one have been within 2% (and the other is out by 4%).

It's all well and good for VW to say that their error will have me travelling at a lower speed than indicated. It isn't up to them to arbitrarily lower the (already low) speed limits by any amount. So now, if I want to travel at the limit, I have to come up with some sort of correction, and then mentally apply it every time I glance at the speedo.

This is really annoying.

[BeigeJet]

Maybe I'm getting old and cranky but if the speedo is reading under actual wouldn't that mean you avoid lots of speeding fines. n:

The other benefit is that if you are travelling just that little bit slower and in an emergency situation your kinetic energy is less and therefore less potential for a major collison or better still aviodance of a collison.

It makes your fuel consumption look good too!

[datracer99]

Maybe I'm getting old and cranky but if the speedo is reading under actual wouldn't that mean you avoid lots of speeding fines. n:

The other benefit is that if you are travelling just that little bit slower and in an emergency situation your kinetic energy is less and therefore less potential for a major collison or better still aviodance of a collison.

It makes your fuel consumption look good too!

According to all reports on golfgti.co.uk and vwvortex the trip computer displays distance travelled and fuel consumption using the figure as displayed in the climate control, so it's more accurate than the speedo reading.

[TDI Dude]

There is all that that has been said above.. but when it comes down to it... really... isnt it better to get there in one piece rather than 2 mins quicker and dead!!!

[gregozedobe]

I'm led to believe that the trip computer (digital) is usually pretty accurate compared with the speedo (analogue). If you have a trip computer but not climate control (like in my T5 Transporter) you can get set your cruise control to 100kmh, reset your trip meter, then display the average speed and compare that with what your speedo is showing you (in my case 96kmh when the speedo was showing 100kmh). This is pretty consistent when driving in flat terrain (in particularly hilly country the cruise control speed can vary slightly).

I believe it is possible to adjust the speedo reading (and the average fuel consumption) by up to + or - 15% using Vac com or the VW dealer tool, but be careful if you are already used to making the mental adjustment (ie driving above the speed limit because you know your speedo reads slow).

[red barron]

I've had my GTI for about 3 weeks now. I love the car, but the only thing i'm trying to get used to is the speedo, especially how it goes from 0 - 80 in increments of 10 and then after that increments of 20. You really have to watch the speedo and it can get a little confusing at first.

It would be handy to have the speed digitally displayed on the MDF like the Holdens but i'm not complaining. My GTI is waaaaaaaaaay better then any of those popular cars that I drive every day for work!!

[edstergtsport]

i am getting really annoyed with the speedo becuz for me to go real-time 100 the speedo needs to shows atleast 110.
Anyway so this is a problem that can be fixed by taking the car back to the dealership?

[jb747]

Maybe I'm getting old and cranky but if the speedo is reading under actual wouldn't that mean you avoid lots of speeding fines.

Yeh, that's why I bought an R32.

It isn't up to VW to arbitrarily lower the speed limit. Most VW owners have no idea that they are mobile roadblocks..

[edstergtsport]

Yeh, that's why I bought an R32.

It isn't up to VW to arbitrarily lower the speed limit. Most VW owners have no idea that they are mobile roadblocks..

Exactly what i was thinking! most of us didn't buy our cars to go 7-9% slower than a Toyota Yaris on the freeway or stay on the left hand lane 100% of the time.
also i actually think its safer to travel the same avg speed as the rest of the cars on the road especially on freeway or country roads where there are a lot of cars going at constant speeds. having accurate speedo also avoids cars constantly trying overtake, changing lanes and cutting infront of me. it saves alot of potential hazards to have accurate speedo.

[Splashalot]

Exactly what i was thinking! most of us didn't buy our cars to go 7-9% slower than a Toyota Yaris on the freeway or stay on the left hand lane 100% of the time.
also i actually think its safer to travel the same avg speed as the rest of the cars on the road especially on freeway or country roads where there are a lot of cars going at constant speeds. having accurate speedo also avoids cars constantly trying overtake, changing lanes and cutting infront of me. it saves alot of potential hazards to have accurate speedo.

And that pretty much sums-up my thoughts Just give us an accurate measure of speed, please Mr VW

SS

[Spoddy]

If the speedo is overstating the true speed, does it also mean that the trip meter is clocking up more distance than is real? Does that mean our cars could show more kms than they should and VW then get more money for servicing more often than is really required? And the car is out of warranty 8000km before it should be?