# Speedo accuracy



## revulike (Jun 15, 2018)

After a brush with a camera van, I'm hoping the mk3 speedo over reads (a lot).
Does anyone have reliable figures on differences?
82 mph for instance.

(M23 just past Gatwick southbound shortly after the 50 limit is lifted.) :?


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## brittan (May 18, 2007)

These are reliable figures which might interest you:


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## powerplay (Feb 8, 2008)

I know from using both my Garmin and Dragy GPS devices when the car is reading 70mph it's actually about 68mph, so there is a small over-read, probably +3 at 80-90 I would guess.


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## leopard (May 1, 2015)

brittan said:


> These are reliable figures which might interest you:


I wouldn't hold comfort in this chart.

Mrs L was done for doing 32 in a 30mph,depends on what the individual Police County's policies are.North Wales being the worst...


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## ZephyR2 (Feb 20, 2013)

leopard said:


> Mrs L was done for doing 32 in a 30mph ...


Or at least that's what she told you.


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## nickyr (Mar 9, 2016)

I've found my speedo to be really accurate, with indicated speeds (at cruise control) matching GPS speeds at 70.

Driving past those speed check indicator things you see at the roadside, it's spot on at 30.


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## Shug750S (Feb 6, 2012)

revulike said:


> (M23 just past Gatwick southbound shortly after the 50 limit is lifted.) :?


That's sneaky, they know everyone is bored stiff after doing 50 down to LGW. I went through there last week just after midnight. Motorway was almost empty, had to really concentrate hard sticking to 50 through the average speed part.

Easy money for the Scamera, as they know a lot of people will put their foot down after the ave speed section ends


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## pcbbc (Sep 4, 2009)

There was a lot of back-pedalling at the start of the year when Anthony Bangham, the chief constable of West Mercia, called on all drivers to be prosecuted even if within the usual tolerance of 10% + 2mph.

Here he is backtracking the very next week.

I would say, unless there were specific circumstances that we are not aware off, that a prosecution for 32mph in a 30 is somewhat harsh. I suspect any half decent solicitor would probably have got that one quashed on the basis of the above "official" guidance which has been accepted as the norm for many, many years.

And as a side note, don't you just love the chief constables surname: Bangham, as in "bang'em up"! :lol:


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## revulike (Jun 15, 2018)

Cheers all.

Looks like the mk3 speedo is quite accurate. Using the sos phones and assuming a mile separation and accurate clock on my dashcam, it comes out around 81 mph.
Annoyingly the location of the scamera was published (I discovered later). No ksi there for 20 years. Site is described as 'exception'.

Sat for the whole limited section on cruise, then pressed on. Quiet traffic, L3 empty, dry road.

I'll wait for a NIP.

I'm rather worried I was caught on the Gatwick spur as well, a few days earlier. Could be 6 points in 3 days. [smiley=bigcry.gif]


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## revulike (Jun 15, 2018)

Update on this:

Received NIP, 80mph. So speedo was about 2mph over.
Accepted SAC instead of penalty.

Ho hum. May as well have gone for the 1.8. :?


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## minsTTerman (Aug 5, 2003)

Unlucky :?

Must admit I usually stick cruise on at 80mph on the basis that with a couple of mph error, I'll be doing 78, which is (just) within the usual tolerances. Have been past a couple of camera vans (one in North Yorks and one in West Yorks) with cruise at 80mph (and too late to react by the time I've seen them) and not had a NIP.

Obviously them sitting somewhere useful and catching the (mostly foreign) drivers skipping red lights and driving down the wrong side of the road, would cause them far too much hassle and probably result in calls of racism. Hey ho.


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## Toshiba (Jul 8, 2004)

But would the 1.8 get upto 80?
Or is that the point, it would mean you couldn't have been speeding ;0)


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## revulike (Jun 15, 2018)

I bought the TT to replace a Smart roadster.
70 in the Smart was fast, 80 was warp speed and I never went any faster!


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