Me again

After the initial hiccups the last 4 months have been trouble free (knock, knock) but one thing is beginning to drive me nuts.

My speedo always shows 5 mph below my actual speed i.e. 25 @ 30, 35 @ 40 etc., any idea why?

Just to clarify, everything is standard, wheels, tyres etc., the speed has been checked following other vehicles and, to be honest, after 35 years of driving you know your speed within a couple of mph.  Not Representative!

What's telling you you're doing 5mph less than you think it is doing?

Erm, the speedometer display.  Not Representative!

@ Pld...was thinking the same ..


@ flunter...Do you have 2 different indicators of speed? One being the speedo and the other being.....?

Ie how do you see 2 different speeds to know there's. A 5mph difference...sorry i may be being thick. GONE 2010 Facelifted 3.6 TDV8 - Stornoway Grey + 22" Overfinch Olympus
HAVE 1999 Discovery 2 GS 4.0 V8 - Silver - Off Road Toy
GONE 2013 L405 4.4 SDV8 Vogue. Black with Silver roofline and 22" s
HAVE 2015 Jaguar XF.

If the speedo display displays 30mph, how do you know it's only doing 25?

Last edited by pld118 on 4th Aug 2014 6:03am. Edited 1 time in total

As I stated in my initial post, I've checked the speed by following other vehicles. When they're doing 30 my speedo shows 25, and the same at other speeds. I checked it against 3 different cars with the same results.  Not Representative!

Ah...understand now...the wiki has a workshop manual and you may get a clue there, but obvoius stuff like tyre wear will make a difference. GONE 2010 Facelifted 3.6 TDV8 - Stornoway Grey + 22" Overfinch Olympus
HAVE 1999 Discovery 2 GS 4.0 V8 - Silver - Off Road Toy
GONE 2013 L405 4.4 SDV8 Vogue. Black with Silver roofline and 22" s
HAVE 2015 Jaguar XF.

Wasn't clear to me in the OP. Sorry.



Last edited by pld118 on 4th Aug 2014 6:03am. Edited 1 time in total

Whilst I find your methodology in determining your vehicles actual speed somewhat dubious, can I suggest in the first instance that you have the car plugged into a diagnostic unit to check if any faults are logged on the ABS system.

first port of call would be to buy or borrow a stand alone sat nav and compare your speed to that.... ... - .- -.




Y. O. L. O.
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I agree with Stan. So many phones have gps, it should be easy to get a passenger to test to for you at a variety of different speeds.

I have that issue with my Disco, but I have oversized tyres that cause the difference.

You say you have standard tyres... What size are they? Previously..
Vogue SE TD6
Defender 90 2.4
Defender 110 TD5
Vogue 3.5 EFI

I have the same issue. Checked by using another satnav and speed display signs on roadside and roughly 20% below actual speed is being registered on speedo. Not sure how to correct it or just live with it

The speed display signs are not particularly accurate...

Like most people my speedo over reads by a tad ( normal ) but if I set a speed warning bong it goes off right on the money , have you checked that ? 2008 MY Supercharged
Rimini Red / Jet
four zone climate
remote park heater
and no ugly kid windows.
magnus satis quod turpis satis