Accuracy of Audi Speedo
Discussion
Yesterday I received an NIP for 80mph on a NSL dual carriageway. It was Easter Sunday, midday, sunny and clear. I had the cruise set to 80 and was just wafting home. I spotted the scamera van miles in the distance and quickly brought my speed down to around 65mph.
Now, I'm not looking for sympathy (not that PH ever offers any for speeding!) and will hold my hands up to it and accept the punishment. Yes, it was clearly there to generate cash as opposed to being a safety issue and people can respond however they want - I will not change my opinion on this.
The point being that I am surprised as to how accurate the speedo was! I always assumed they under-read by around 5-10% and my actual speed would have been more like 75mph. This is more of a warning to other Audi drivers that it appears they are extremely accurate! The car is a 2016 S5 and I have the digital readout displayed but frequently rely on this assumption when travelling motorways with overhead gantrys. I would hate for anyone else to fall into this trap so if you have the same / similar car be aware there is a likeilhood of zero tolerance in the readout.
Now, I'm not looking for sympathy (not that PH ever offers any for speeding!) and will hold my hands up to it and accept the punishment. Yes, it was clearly there to generate cash as opposed to being a safety issue and people can respond however they want - I will not change my opinion on this.
The point being that I am surprised as to how accurate the speedo was! I always assumed they under-read by around 5-10% and my actual speed would have been more like 75mph. This is more of a warning to other Audi drivers that it appears they are extremely accurate! The car is a 2016 S5 and I have the digital readout displayed but frequently rely on this assumption when travelling motorways with overhead gantrys. I would hate for anyone else to fall into this trap so if you have the same / similar car be aware there is a likeilhood of zero tolerance in the readout.
Interesting.....latest gen VAG cars with the full digital set up (Golf 8, Octavia IV, Formentor etc) appear to be around 2-3mph out compared to GPS at 70mph, so certainly much tighter tolerance than say my Golf 7 GTD example, which was a round 5mph at the same speed. I'd have assumed your S5 to be running the same sort of speedo hardware/software as the Golf 7, so I an suprised to see you have effectively zero tolerance.....?
Have you checked it against a standalone GPS?
Have you checked it against a standalone GPS?
MattyD803 said:
Interesting.....latest gen VAG cars with the full digital get up (Golf 8, Octavia IV, Formentor etc) appear to be around 2-3mph out compared to GPS at 70mph, so certainly much tighter tolerance than say my Golf 7 GTD example, which was a round 5mph at the same speed. I'd have assumed your S5 to be running the same sort of hardware/software as the Golf 7, so suprised to see you have zero tolerance.....?
Have you checked it against GPS?
This is interesting. I haven't to be honest as I use the in built sat nav which doesn't display speed. Have you checked it against GPS?
8IKERDAVE said:
This is interesting. I haven't to be honest as I use the in built sat nav which doesn't display speed.
Might be worth a run out with a "speedbox" type app on your phone.....see how it fairs. I guess it is indeed possible you've been caught by a poorly calibrated camera, although I would expect this to be quite unlikely.You've also not been given the 10% + 3 margin either?
I'm not going to give you any grief for speeding because we all do it. But I've tested my newest car's speedo (2014 Porsche which I imagine has similar software to your Audi) with a GPS speedometer app and the margin of error is not a percentage. In fact between 60mph and 90mph, the car speedo overreads pretty consistently by 3mph. Between around 30-50mph the difference is 2mph. So the speedo is accurate, but it's just set to display a slightly higher value than true speed.
You can test this very easily using any smartphone. Just make sure you have the speedometer app running for a while before conducting the test, and make sure you do it on a wide open road so that you have data from as many satellites as possible, to give you the best GPS precision. Also, make sure you keep a steady speed and wait a few seconds after changing speed before taking a new reading. This will allow the GPS speed to stabilise.
You can test this very easily using any smartphone. Just make sure you have the speedometer app running for a while before conducting the test, and make sure you do it on a wide open road so that you have data from as many satellites as possible, to give you the best GPS precision. Also, make sure you keep a steady speed and wait a few seconds after changing speed before taking a new reading. This will allow the GPS speed to stabilise.
I've driven endless VAG products.
My experience (currently on a 2021 Tiguan, but similar on a bunch of Audi and VW from last couple of years) as real GPS speed vs digital speedo
On new rubber, 100mph (hypothetical) = 97-98mph
On 15,000 mile old tyres, 100mph (hypothetical) = 96-97mph
80mph would probably be 78mph on my current car, so borderline on the limit of triggering. Obviously the adaptive cruise also does regularly fluctuate +/- 1mph when accelerating or on gradients.
My experience (currently on a 2021 Tiguan, but similar on a bunch of Audi and VW from last couple of years) as real GPS speed vs digital speedo
On new rubber, 100mph (hypothetical) = 97-98mph
On 15,000 mile old tyres, 100mph (hypothetical) = 96-97mph
80mph would probably be 78mph on my current car, so borderline on the limit of triggering. Obviously the adaptive cruise also does regularly fluctuate +/- 1mph when accelerating or on gradients.
Last two cars I have had the speedo' has over read by 2 or 3 mph so any angelic
drivers out there stick to what it reads and never get caught out. 70 mph is actually 67-68 etc.
I have had so many nearlys lately. I got away with just a speed awareness course a couple of years ago, I must be sad because I actually enjoyed the course.
Feel for you.
drivers out there stick to what it reads and never get caught out. 70 mph is actually 67-68 etc.I have had so many nearlys lately. I got away with just a speed awareness course a couple of years ago, I must be sad because I actually enjoyed the course.
Feel for you.
Is the car on OEM wheels & the correct tyre size, and have you checked "winter tyres" isn't selected in the setup menu?
Although the camera vans can catch people from a fair distance, it's not when it's so far away you can't see what it is. If you scrubbed off speed straight away, I'd be surprised it got you doing 80 if that was the maximum you'd been doing.
I've never come across a VAG speedo which doesn't over-read by a bit. They will be closest when the tyres are brand new, but still over-read by a few mph at motorway speeds to make sure they never under-read (which is a legal requirement).
It would be worth either checking the speedo by timing the car across a known distance or comparing with reported GPS speed on a sat-nav / phone.
The other possibility is that there were two camera vans along the route and you only spotted one......
Although the camera vans can catch people from a fair distance, it's not when it's so far away you can't see what it is. If you scrubbed off speed straight away, I'd be surprised it got you doing 80 if that was the maximum you'd been doing.
I've never come across a VAG speedo which doesn't over-read by a bit. They will be closest when the tyres are brand new, but still over-read by a few mph at motorway speeds to make sure they never under-read (which is a legal requirement).
It would be worth either checking the speedo by timing the car across a known distance or comparing with reported GPS speed on a sat-nav / phone.
The other possibility is that there were two camera vans along the route and you only spotted one......
MattyD803 said:
You've also not been given the 10% + 3 margin either?
What 10% + 3 margin? There never has been that margin. The most police forces will give is 10%+2, and they don't HAVE to give you that margin. They could prosecute at 1mph over the posted speed limit. They give a margin because they would lose any public sympathy with a zero tolerance approach, and the costs involved in prosecuting the number of people exceeding the limit by a small margin would be enormous.SkodaIan said:
Is the car on OEM wheels & the correct tyre size, and have you checked "winter tyres" isn't selected in the setup menu?
Although the camera vans can catch people from a fair distance, it's not when it's so far away you can't see what it is. If you scrubbed off speed straight away, I'd be surprised it got you doing 80 if that was the maximum you'd been doing.
I've never come across a VAG speedo which doesn't over-read by a bit. They will be closest when the tyres are brand new, but still over-read by a few mph at motorway speeds to make sure they never under-read (which is a legal requirement).
It would be worth either checking the speedo by timing the car across a known distance or comparing with reported GPS speed on a sat-nav / phone.
The other possibility is that there were two camera vans along the route and you only spotted one......
I thought the same to be honest. I definitely didn't exceed 80 as the cruise was set as such. I will dig into the menus and see if the settings are right, thanks for that. The car is completely standard and AFAIK they are all on 20" wheels. Although the camera vans can catch people from a fair distance, it's not when it's so far away you can't see what it is. If you scrubbed off speed straight away, I'd be surprised it got you doing 80 if that was the maximum you'd been doing.
I've never come across a VAG speedo which doesn't over-read by a bit. They will be closest when the tyres are brand new, but still over-read by a few mph at motorway speeds to make sure they never under-read (which is a legal requirement).
It would be worth either checking the speedo by timing the car across a known distance or comparing with reported GPS speed on a sat-nav / phone.
The other possibility is that there were two camera vans along the route and you only spotted one......
If there was a second van further down I had reduced down to 70. A bit like buying a burgular alarm after you have been burgled!
LunarOne said:
What 10% + 3 margin? There never has been that margin. The most police forces will give is 10%+2, and they don't HAVE to give you that margin. They could prosecute at 1mph over the posted speed limit. They give a margin because they would lose any public sympathy with a zero tolerance approach, and the costs involved in prosecuting the number of people exceeding the limit by a small margin would be enormous.
My mistake, +2 it is......On both our cars, a Laguna and a DS3, we have digital limiters/cruise with a display, and an analogue speedometer. I also often have a GPS speed via Google Maps on Android.
On both the speedo reads higher than the limiter, e.g. 70 on the limiter produces maybe 73-75 on the speedo. Maps shows slightly lower than the limiter but for some reason I don't totally trust it.
You start getting done at 79 so I wouldn't chance 79 or higher on cruise/limiter.
On both the speedo reads higher than the limiter, e.g. 70 on the limiter produces maybe 73-75 on the speedo. Maps shows slightly lower than the limiter but for some reason I don't totally trust it.
You start getting done at 79 so I wouldn't chance 79 or higher on cruise/limiter.
LunarOne said:
What 10% + 3 margin? There never has been that margin. The most police forces will give is 10%+2, and they don't HAVE to give you that margin. They could prosecute at 1mph over the posted speed limit. They give a margin because they would lose any public sympathy with a zero tolerance approach, and the costs involved in prosecuting the number of people exceeding the limit by a small margin would be enormous.
Wouldn't be quite so hasty:https://www.evo.co.uk/news/22591/new-info-reveals-...
It is 10%+3 for at least 2 forces.
I remember reading somewhere that there's a setting in Porsches (and probably all VAG cars) which can be controlled via PIWIS (i.e. not user-modifiable) to make the car display either the actual calculated speed, or one with a safety margin applied. I cannot confirm personally whether this is true. I think I'd personally prefer to see the real speed and add a safety margin in my head rather than being deliberately misinformed. Because when I'm being good, I drive at an indicated 73mph knowing that it actually translates to a real 70mph.
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