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MG MGF Technical - Speedo accuracy

Anyone know if the speedo on the MGF is known to be inaccurate, please? Today I was driving on the motorway using a portable satellite navigation system and noticed that the speed shown on the sat nay device was some 10 mph below the speed shown on the speedo.
Steve Mcleod

Steve, most speedos are quite inaccurate. I tested the accuracy of the speedo in my F some years using the revs and gear ratios. At low speeds the speedo under-read (e.g. showing 40mph when I was doing 41mph) the speed and at high speeds it was over-reading (e.g. showing 100mph when I was doing 97mph).

Obviously, the size of the tyres (and the amount of tread on them) is a factor in the accuracy of the speedo.

Ralph
Ralph


Most speedos in most cars are about 10% out.
Martin

I am running 16" wheels Front 195/45. When the speedo said 100mph the GPS said 95mph.
Steve Ratledge

>Most speedos in most cars are about 10% out.

So is the MGF/TF
*approved by gatso* ;)
Dieter

Compared to my SatNav, my '98 F reads around 1-2mph low at an indicated 30mph, rising to around 8-9mph low at an indicated 90mph (tested on the continent). The car is running standard 15 inch rims with standard fitment tyres etc.

(By way of comparison, the ZS is spot on at 30mph, and only 2mph low at an indicated 90 (under similar test conditions)).

Mike H
Mike Hall

This thread was discussed on 08/11/2005

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