Incorrect Speedometer - Golf mkVII?

[GolfVII]

South Australia has just recently set up a heap of point to point cameras one is on the way to Pt Wakefield, In recent weeks we made the trip a couple of times and the first time I took the MK7 up using the ACC all the way set on 111km/h. I don't use a GPS, got one just find they are annoying and not needed when signs and a good old road map works fine on the free-way (looking for a house I have never been to, then I use the GPS.) The first trip up and back we used the same speed and did not get a fine. I was passing cars and they all would look at me like, "you are speeding!" but with no fine in the mail they were wrong.

The second time we went up I needed to drive my father in-laws Mk6 up with the wife following behind in the Mk7, when I set the speed on the Mk6 to 110km/h my wife set the ACC to 115km/h. while on the phone I asked what speed was showing on the MK7? the speed was showing as 107km/h.... I adjested the CC on the Mk6 to 113km/h and then the Mk7 moved up to 110km/h. This was all before the Point to Point Cameras. Again we did not get a fine for travelling over the speed limit. When discussing this with my father in law he said that his GPS for 110km/h shows the Mk6 doing 113km/h. This left me feeling releived that the Mk7 was bang on the money for speed travelling to speed displayed on the dash.

While travelling along this road in the Mk7 we passed quiet a few cars and all with dirty looks of "you are speeding", one car we passed was going at least 100km/h and this person started flashing their lights at us, I flashed my snow light at him and continued along at my speed that had been tried and tested.

Here in SA the Motor Accident Commission had a add on TV telling people to "wipe of 5" this was targeted at the "SPEEDERS" but people who were doing the right speed on the roads got brain washed by this campaign and now you find people doing 51km/h in a 60 zone.... I feel this campaign has hit the wrong audience and has created unsafe drivers.

When I was 18 I passed the one off driving test you could do to get your P plates without needing to fill out the log book. This test was about 90min long and the instructor would take you through everything covered in the log book. This was back in a time when 60km/h was the minimum speed for all roads, no 50 zones. One of the roads the instructor made me drive down had a heap of spoon drains and was a back street I did not know, while going down this road I did not exceed 50km/h because one, by the time you got to 60 you would have to break heavy and two I did not know the road and how deep the spoon drains were. After I finished the 90min test we got back to the centre where started from and I was informed that, "I did not pass the test" this was for two reasons. The first was I took to long to pull out on a main road (two cars parked on the side of the road and a tree in the way so I waited for the car I could safely see had passed before moving on) and the second was I drove to slow in the back streets..... I was gob smacked with these comments, so I put up my arguments to why these situations had played out. The instructor consulted another instructor with my reasoning, they both came back and said I passed.

My point is Laws seem to be always made by people who have no idea about real world factors. Australia needs to stop making people concerned about what speed they are doing and have people complete further education on driving so they know what to do in a situation where they need to think quickly. Because loosing control at 60 is still as dangerous as loosing control at 100 and If you don't know how to control the vehicle in these situations it can be deadly as you see on the news around long weekends

The ADR rules for cars should be a car produced from the manufacture should display the correct speed at time of production, obviously this is going to change as tyres wear away, but that's only going to slow your speed by a small amount as they wear. These speed differences from different car manufactures are just going to cause road rage and situations stated in this thread.

After this long post, My Mk7 Golf seems to be spot on the mark for speed travelling to speed displayed.

[brad]

After much fiddling my Octavia is near enough 1=1. It's made me more aware of the speed limit and I don't have the mentality of " I can afford to drift over as there's some leeway."

It's made me a more law-abiding driver. I still pass a lot of cars though.

I never realised they were staring at me because they thought I was speeding - I assumed it was my develishly good looks.

[Transporter]

How do you know that the GPS speed is always 100% accurate?



I know that my T5's odometer is 5 km/h faster and I admit that I use the Navman's displayed speed as well, but after what once happened to me, I don't rely on it.
Anyway, while I was travelling at almost steady speed I've noticed that I've passed my turn and the GPS didn't say "turn left", so I'd quickly checked the GPS and surely it was frozen.

Just imagine that you trust it more than your car's odometer and got a massive fine for speeding, just because it's frozen or it lost a few satellites and the accuracy was out.

Oh, and my Amarok's speedo is almost 10km/h faster. I just don't see it as a big problem and am glad that VW designed it that way. Lesser chance to be booked for the speeding.

[Idle]

When I had a Mk6, its speedo was well out — 100 on the dial was near enough to 92 and to travel at 110 I had to be showing 120.

Now have Mk7 and its quite a bit closer to accurate — haven't been able to check it yet (the radar devices on the Hume have been taken down, and I've not been to Geelong lately), but estimate it's within 3%.

Travelling at indicated limit no longer makes me a mobile roadblock, but a lot of vehicles do pass me.

[Guest001]

Just did an interesting test.... Recently got a ODB2 bluetooth device. When comparing the EHS and GPS speeds on my phone, they are roughly within 0.5 km/H of eachother, however both the digital speed and needle display about 4-5 km/H above these.....

So I guess it is hard to tell whether the odo is over reading by much.... There will Def be more discrepancy as the tyres wear, but the EHS speed will also be out of this is the case?

Unless they can do some trickery that works out what the rolling Diameter of the tyre should be based on the ABS sensors and performs some autocorrection of the value to the ECU?

I Could just be full of s#!t though....

The ODO has no correlation to the speedo reading.
You can alter the pulses for the speedo and it wont alter the ODO which is much truer that the speedo reading.

[brad]

How do you know that the GPS speed is always 100% accurate?

quality item and double checked with someone else

I know that my T5's odometer is 5 km/h faster and I admit that I use the Navman's displayed speed as well, but after what once happened to me, I don't rely on it.
Anyway, while I was travelling at almost steady speed I've noticed that I've passed my turn and the GPS didn't say "turn left", so I'd quickly checked the GPS and surely it was frozen.

Just imagine that you trust it more than your car's odometer and got a massive fine for speeding, just because it's frozen or it lost a few satellites and the accuracy was out.

Oh, and my Amarok's speedo is almost 10km/h faster. I just don't see it as a big problem and am glad that VW designed it that way. Lesser chance to be booked for the speeding.

I'm not using the GPS as a permanent speedometer. Once I know the calibration variance the speedometer becomes the measurement device. I've had a GPS lock up as well.

If you know it's 10kmh out then the 10kmh variance is pointless & not a safety "feature". It's like trying to fool yourself by setting your watch 10 minutes faster.... then speeding through a school zone because your watch is wrong.

I work with accurate gauges and spend a lot of other peoples money to make sure they are calibrated & accurate. I'd look like a fool if I suggested we make our gauges read a "little bit safe".

As I've said before - if there's a tailback on the highway due to somebody driving slow there's probably a law abiding citizen at the front in a VW thinking they are doing the speed limit.

It seems odd the speedo is calibrated for those that feel inclined to break the speed limit & those with the ability to drive with their speed within the posted limit are made to look like fools.

[Guest001]

quality item and double checked with someone else





I'm not using the GPS as a permanent speedometer. Once I know the calibration variance the speedometer becomes the measurement device. I've had a GPS lock up as well.

If you know it's 10kmh out then the 10kmh variance is pointless & not a safety "feature". It's like trying to fool yourself by setting your watch 10 minutes faster.... then speeding through a school zone because your watch is wrong.

I work with accurate gauges and spend a lot of other peoples money to make sure they are calibrated & accurate. I'd look like a fool if I suggested we make our gauges read a "little bit safe".

As I've said before - if there's a tailback on the highway due to somebody driving slow there's probably a law abiding citizen at the front in a VW thinking they are doing the speed limit.

It seems odd the speedo is calibrated for those that feel inclined to break the speed limit & those with the ability to drive with their speed within the posted limit are made to look like fools.

It is not calibrated for fools. It is done to comply with Govt legislation, plain and simple.
By doing so it absolves manufacturers from being sued if owners get fined for speeding due to a slow reading speedo.

If your watch is fast and you are aware it is and you speed its your own fault isnt it.

It wont only be a VW at the front ALL CARS SPEEDOS READ FAST BY LAW.

Only difference is the variance as to how much.

[Transporter]

I work with accurate gauges and spend a lot of other peoples money to make sure they are calibrated & accurate. I'd look like a fool if I suggested we make our gauges read a "little bit safe".

I agree Brad, but even your accurate gauges aren't 100% accurate, there is always some tolerance limit.

The needle of the speedo is thick enough for the very accurate speedo to get you in the trouble, all what's needed is that the driver changes the seating position slightly not viewing the speedo absolutely parallel and from directly above and he/she could be 5-10km over the speed limit.

I'm so used to my T5 that I know what speed I'm doing with a very high degree of accuracy and could safely say that I even don't need the speedo. But, I can't say that I'm that good at judging the speed when I drive the car I don't drive every day. it usually takes me 5,000km to 10,000km to calibrate my senses.

[GolfVII]

I cant wait to take the Mk7 on a run to Melbourne as they have the mounted speed displays on the highway over there and when we went over in the Eos we set CC on at 100km/h and the display read 97km/h. We then checked the Navman GPS and it said we were travelling at 97km/h.

All cars have a variance and I was surprised the Mk7 was so accurate.

I had a Datsun Homer with sunrisers rims with 4x4 muddies on it and after a few years driving I got two speeding fines in a matter of weeks both were for doing 71 in a 60 zone. I had stuck to 35mph and that should keep me under 60km/h but due to the large tires this had put the speedo out a fair bit. This was back before GPS units were around so we used our new car to compare and while doing 35mph in the Homer the Starwagon showed around the 70km/h mark.

Point is changing tyres/wheel size will put your speedo out, worn out tyres will affect the speed you travel. Its all about the diameter/circumstance of the wheel, bigger wheels more distance travelled in one rotation. I heard you can have your speedo recalibrated but never look in to it.

I like the fact the Mk7 is so accurate no need to worry when I see these "Safety Cameras"

[Mountainman]

All cars have a variance and I was surprised the Mk7 was so accurate.

Not very accurate in my Mk7 with 5% out but it is better than a friend's Mk5 at 6% and my Subaru at 7%. My old '97 Camry from many years ago was spot on at any speed and I liked that. It annoys me that I'm really guessing all the time by travelling at an indicated 105 in 100 zones and often 110 just to sit with the surrounding traffic because they think that they can get away with it. Almost without exception though they all drop back to an indicated 100 when the fixed speed camera comes up. So much for confidence in speedo recalibrating and sat nav readouts, heh? It seems like when speed really matters that the speedo readout is what really counts to most of us.

[GolfVII]

I wonder if when calibrating the Mk7 speedo they used a wheel size ?225?/40 R18?

That is what is run on my Mk7.

Be interesting to know if anyone with a GTI, R-line pack or optioned a 18" rim on a Mk7 find their speedo to be correct?

[brad]

Almost without exception though they all drop back to an indicated 100 when the fixed speed camera comes up. So much for confidence in speedo recalibrating and sat nav readouts, heh? It seems like when speed really matters that the speedo readout is what really counts to most of us.

I pass a minimum of 4 HWP cars & a 2-way speed camera most work days. So many idiots that are at legal speed and they jam their brakes on when they see the HWP car or go through the 60kmh fixed speed camera doing 40kmh.

[par2]

I wonder if when calibrating the Mk7 speedo they used a wheel size ?225?/40 R18?

That is what is run on my Mk7.

Be interesting to know if anyone with a GTI, R-line pack or optioned a 18" rim on a Mk7 find their speedo to be correct?

I am checking this out today. I have GTI with 225/40 R18 tyres, only 4,500km on the odo. I have been using the same GPS (a Tom Tom) for 4 years, setting cruise control speed based on it. I see at least one fixed and two mobile revenue cameras each way to work every day, and have never been fined. Hence, I assume the GPS is accurate. Will post up the results when I have checked.

[MGV]

Yeah, i reckon the GPS speed is pretty good. I've been checking my Tom Tom against a free phone application called SpeedView with identical results (within +/- 1kph). Setting my cruise to 118 (110 on GPS) on the M1, been past plenty of coppers with radar with not an issue.

[Mountainman]

I have had a chance to check my speedo against my Garmin now over a much wider range of speeds and have found that it is not consistently 5% fast over the whole speed range. At speeds up to 110km/h it is 5% optimistic but over that it just reads 6km/h fast, all the way through to 160km/h. So 60=57, 80=76, 100=95, 120=114, 140=134 and 160=154.