| Car speedometer speed v GPS speed 12:05 - Sep 13 with 3166 views | GavTWTD |
Am I right in thinking that the car speedo is set slower than the actual speed of the car?
I notice that when I go 75 (car speedo), GPS (Google maps) says I'm going 70, so I've been setting my cruise control at 75.
GPS has to be more accurate, right? |  |
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| Car speedometer speed v GPS speed on 12:06 - Sep 13 with 3130 views | Herbivore |
Think car speedos are notorious for overestimating by about 10%. |  |
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| Car speedometer speed v GPS speed on 12:11 - Sep 13 with 3098 views | Keno |
My Speedo's make everything seem at least 10% bigger but then it is a bit of a tight squeeze to fit everything in.
Hope that helps |  |
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| Car speedometer speed v GPS speed on 12:16 - Sep 13 with 3066 views | _clive_baker_ |
I always thought that but then those electronic warning signs on the side of the road that tell you how fast you're going are generally the same as what my dashboard is saying. Could be that they're both inaccurate I guess. |  | | |
| Car speedometer speed v GPS speed on 12:18 - Sep 13 with 3057 views | bluelagos |
Pretty much. Your GPS/Sat nav will be more accurate than your speedo.
The police guidelines also give you 10% + 2 - but they can still do you if only 1 mph over. In practice they don't - unless you're unlucky and meet the local station knobber which pretty much every station has at least one of.
(all according to an ex traffic plod) |  |
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| Car speedometer speed v GPS speed on 12:39 - Sep 13 with 2963 views | Tangledupin_Blue |
As I understand it...
The speedo must not show a speed slower than the vehicle is travelling. The margin of error allows that it may show a faster speed of 10% plus 6.25 mph. So a vehicle travelling at wxactly 50mph may show a speed of anything between 50mph and 61.25mph.
Vehicle manufacturers always send vehicles out of the factory callibrated to show a speed a bit above the actual speed so that, when driving conditions, tyre conditions, vehicle modifications etc change, those changes will not make the vehicle 'illegal'. |  |
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| Car speedometer speed v GPS speed on 12:50 - Sep 13 with 2896 views | Daninthecampo |
Gps will always have a delay so not fully accurate, GPS on phones are also not as good as specific GPS units, but probably still more accurate than your speedo |  | | |
| Car speedometer speed v GPS speed on 12:54 - Sep 13 with 2875 views | homer_123 |
I guess if your doing 113mph, whether its the speedo or GPS, you're likely breaking the speed limit. |  |
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| Car speedometer speed v GPS speed on 13:03 - Sep 13 with 2835 views | Swansea_Blue |
| Car speedometer speed v GPS speed on 12:11 - Sep 13 by Keno |
My Speedo's make everything seem at least 10% bigger but then it is a bit of a tight squeeze to fit everything in.
Hope that helps |
You should get yourself a pair with braces, to keep everything contained
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| Car speedometer speed v GPS speed on 13:19 - Sep 13 with 2749 views | Churchman |
Yes. GPS is more accurate and speedometers have always over read. I notice it particularly with Mrs Cs car where the gps info is more prominent on the satnav. Thinking of another thread, in the dim and distant last century I had my car up to 126mph indicated (don’t ask), yet the published max for the car was 122. My guess is that it was doing about 116mph
As it goes, these days I set cruise control to the speedometer to the speed limit in camera areas, roadworks etc just to give myself a little leeway with average speed cameras. The ‘time loss’ for a few mph is meaningless and if it hacks off a stressmonster behind, they’ll get over it. [Post edited 13 Sep 2023 13:22]
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| Car speedometer speed v GPS speed on 13:22 - Sep 13 with 2723 views | Zx1988 |
I have exactly the same with my car.
Indicated 75mph gives a GPS speed of 70mph. It must be accurate, as I've never encountered any issues with speed cameras/speed traps etc., | |
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| Car speedometer speed v GPS speed on 14:48 - Sep 13 with 2576 views | Nutkins_Return |
| Car speedometer speed v GPS speed on 12:54 - Sep 13 by homer_123 |
I guess if your doing 113mph, whether its the speedo or GPS, you're likely breaking the speed limit. |
Yes but nobody would be daft enough to go 113mph! | |
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| Car speedometer speed v GPS speed on 17:10 - Sep 13 with 2448 views | factual_blue |
Car speedometers can, I think, overstate your speed by around 10%. They can't understate it at all, for obvious reasons. I think the reason is probably to prevent the high cost of 100% accurate calibration of mass-produced speedometers; traffic police have calibrated and 100% accurate meters.
If you compare the speed on your sat nav (ie GPS) with that on a roadside sign that shows your speed, they'll match. Your speedometer will tell you you're doing more than that. |  |
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| Car speedometer speed v GPS speed on 17:36 - Sep 13 with 2404 views | Tangledupin_Blue |
| Car speedometer speed v GPS speed on 17:10 - Sep 13 by factual_blue |
Car speedometers can, I think, overstate your speed by around 10%. They can't understate it at all, for obvious reasons. I think the reason is probably to prevent the high cost of 100% accurate calibration of mass-produced speedometers; traffic police have calibrated and 100% accurate meters.
If you compare the speed on your sat nav (ie GPS) with that on a roadside sign that shows your speed, they'll match. Your speedometer will tell you you're doing more than that. |
They can overstate by 10% + 6.25 mph. | |
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