MK5 Golf GTI

All Things Mk5 => Mk5 General Area => Topic started by: Pesky jones on April 14, 2015, 02:04:12 pm

Title: Spedo accuracy
Post by: Pesky jones on April 14, 2015, 02:04:12 pm
Say you're going 80mph, does anyone know if your're actually going 80? Or less?
Title: Re: Spedo accuracy
Post by: Matthewsimone on April 14, 2015, 02:45:52 pm
http://click2how.com/your-speedometer-wrong-can-drive-faster/
Title: Re: Spedo accuracy
Post by: StuF on April 14, 2015, 02:51:24 pm
My digital speedo reads 80 mph where my analogue gauge shows around 72/74mph  when on the motorway
Digital one is more accurate I guess!
Title: Re: Spedo accuracy
Post by: xjay1337 on April 14, 2015, 03:01:27 pm
Quote from: Peskyjones on April 14, 2015, 02:04:12 pm
Say you're going 80mph, does anyone know if your're actually going 80? Or less?


My dash says 80 my Polar MFD which is wheel speed sensor says 75
Title: Re: Spedo accuracy
Post by: lukemk5gti on April 14, 2015, 03:13:53 pm
I've always wondered this after seeing one of those speed digital display signs showing a different speed to what I'm doing.

At least by the looks of that link you're actually travelling slower than your speedo shows.

I might have cruise control on at 100km/hr in a 100km/hr zone and when I see a speed camera I still hit the breaks on occasion thinking what if the speedo is wrong!!
Title: Re: Spedo accuracy
Post by: xjay1337 on April 14, 2015, 03:36:02 pm
The European regulation, ECE-R 39, states that the speed indicated must never be lower than the true speed or higher by more than one-tenth of true speed plus four kilometers per hour (79.5 mph at a true 70).

You will never be going faster than your displayed speed.
Title: Re: Spedo accuracy
Post by: usmangti on April 14, 2015, 05:04:09 pm
Quote from: xjay1337 on April 14, 2015, 03:36:02 pm
The European regulation, ECE-R 39, states that the speed indicated must never be lower than the true speed or higher by more than one-tenth of true speed plus four kilometers per hour (79.5 mph at a true 70).

You will never be going faster than your displayed speed.

Is it also true that a camera or speed gun can only catch you above the speed limit after 10% plus 2mph? Ie in a 30 would have to be driving at least 35mph?
Title: Re: Spedo accuracy
Post by: xjay1337 on April 14, 2015, 05:24:15 pm
CPS recommend only pursuing cases where the speed is 10% + 2.
You can (technically) be done for doing 1mph over the speed limit. But practically it won't happen.
Title: Re: Spedo accuracy
Post by: andyR43 on April 14, 2015, 07:18:50 pm
Quote from: usmangti on April 14, 2015, 05:04:09 pm
Quote from: xjay1337 on April 14, 2015, 03:36:02 pm
The European regulation, ECE-R 39, states that the speed indicated must never be lower than the true speed or higher by more than one-tenth of true speed plus four kilometers per hour (79.5 mph at a true 70).

You will never be going faster than your displayed speed.

Is it also true that a camera or speed gun can only catch you above the speed limit after 10% plus 2mph? Ie in a 30 would have to be driving at least 35mph?

I had to attend a speed awareness course for travelling at 33mph in a 30mph zone. Caught by a camera van, just after pulling away from traffic lights and the road merging from 2 lanes into 1 so filtering into the traffic!!!