'06 GS speedometer Inaccuracy by 10mph

[dubai888]

Model: 2006 Lexus GS430 Full Options (Middle East Version)

here is what i obsorved myself (using stopwatch and odometer) and i confirmed using digital readings from the Console > "Info" > Trip info

Speedometer - My reading - difference
--------------------------
55 km/h - 50 km/h
100 km/h - 92 km/h
128 km/h - 119.5 km/h
140 km/h - 131.25 km/h
200 km/h - 187.5 km/h

My 00' Opel Omega 3.0 shows at 140 km/h a reading of 137.5 km/h which i finds it hard to understand ... how a '00 model car more precise than '06 car !!!!!

can somebody from US/Canada test ... is it only us from UAE/Middle East .... is it only my car ?

[ajcsanders]

I have observed the exact same thing on my car - I also have an Asia Pacific (middle east) version, except that mine is a GS300.

I understand that all modern cars have a built-in innacuracy - I think it has something to do with speed limits, but not sure.

You can confirm that the car 'knows' what speed it is doing by using the following trick:
- set the cruise control at a fixed speed, say 120 kmh
- go to the Info / Trip Info screen
- press RESET
- your 'average' speed will show you have fast you are really going

I've noticed the same thing on my 02 Mercedes CLK, and a bunch of other cars i've had.

[Nauticalx]

There are standards (at least in the US ) on how accurate a speedo must be. I believe its within 3 mph, if urs is outside that get it checked up. Sounds like it may be as simple as programming the ECU with the right tires or as simple as lexus redesigning the speedo notches and replacing it. Nevertheless I think you may need to get lexus involved as this probably goes beyond anything your dealer can do since mora thna one vehicle is affected.

[flipside909]

Factory threshold for the speedometer should be +/- 3.