Thread: D4 Speedo v GPS

My D4 speedo is around 4k's slower than my Garmin GPS speed.

I think its case of living with it.

The speedo is allowed to have a max error of 10% over - ie if the car is actually doing 100kph the speedo can read up to 110kph.

However the opposite is not allowed - the speedo cannot read less than actual speed.

The above applies to cars manufactured since about 2005/06. - ADRs.

So if you speedo is reading fast that is OK.

Garry

Originally Posted by LeaRoy

Having tried to protable type GPS in my D4 I would like to know how accruate the speedo is in the D4.

According to both GPS the speedo is about 6km a hour faster.

I have the stardard 18" wheels and tyres on as supplied by the dealer.

Is this normal or is it something I should have checked by the dealer?

Hi Learoy, I have the D4 3.0 with 19" wheels and standard tyres. Mine is between 4 - 5 Kph faster than than the speed on my GPS.
I am told by ULR that they do this on purpose.
Cheers, Craig

Originally Posted by mowog

My D4 speedo is around 4k's slower than my Garmin GPS speed.

I think its case of living with it.

Doh...

Make that faster.

Actual 96k via GPS, Displayed by speedo 100.

Maybe this is why the LR satnav has no speed display option.

Im sure the manufactures also allow for tyre wear in the speedo design. id say its almost 2% allowance just for that.
Steve

Originally Posted by Jim621

Im sure the manufactures also allow for tyre wear in the speedo design. id say its almost 2% allowance just for that.
Steve

That's going the wrong direction as the speedo will read faster again as the tyres wear.

I'm a cynic and think that LR does it to give the impression of better fuel economy.

The GPSR will be more accurate provided you maintain a constant speed for a few seconds in a straight line.

All car speedos over-read so you can't sue the manufacturer when you get a speeding ticket. This is by design.

With 19s, 18s etc you are referring to the rim diameter which is not related to the tyre diameter which is what is important for considering the effect on the speedo.

The D3 computer actually has a tire Diameter figure. Assuming the D4 is the same, with the right tool, just change the tire diameter.

Cheers,
AP
P.S. mine is now dead on....