Thread: For fast drivers who use the speed limit leeway..

wonder why vehicle manufacturers dont use gps to give speedo readings? I mean factory fitted not suction rubbered to your windscreen. Once done there would never be any contradiction about the speed you are driving at. Now, who do we need to speak to to make this a law for all vehicles assembled after say....end of 2010. It only requires a small screen in front of the driver......

Originally Posted by ramblingboy42

wonder why vehicle manufacturers dont use gps to give speedo readings?
<snip>......

In fact the Law, at least in NSW does not recognise GPS as an accurate instrument for reading speed.

Apparently not sufficiently reliable enough for legal purposes. i.e. don't work in tunnels, thick cloud and heavy rain etc etc.

That and the fact that the US military can turn the system off when ever it feels like it. (As they did in Gulf War Mk1 - allowed coalition forces a pre-designated time window each day to get a GPS fix then had to use inertial systems for the remainder of the day.)

I have a 96 Update TDI.Yesterday I checked my speed against a GPS.Speedo showed 110KPH actual GPS speed 105KPH.My tyres are half worn and are the recommended 235 70/16.Now if I check my odometer against the usual 5km posts which are in 1 km stages it was spot on at the 5k mark.Now how come the odometer is accurate but actual speedo is out 5 KPH?
Anyone?

Over how long did you test the speed for, the longer the test period the more accurate the GPS will be. Was it flat road with out bends and rises?

from my experience GPS units like average speeds not acurate speed checks at one particular moment, it said i was skiing at over 80 km/hr when i clearly wasnt. this was some years ago and they have come along way baby!

Originally Posted by Disco44

Now how come the odometer is accurate but actual speedo is out 5 KPH?
Anyone?

Sounds like normal Land Rover tolerances, ie: close enough is good enough .


Seriously, it's probably designed that way. New tyres might add 2-3kph to the real life speed compared to your current ones.

Yes my RRC 92 with electronic speedo is 5% fast and the odometer spot on with 205x16 tyres or 245.70X16 .
Regards Philip A

Don't people understand that the odometer and the speedometer are two discrete mechanisms that use the same sensor to calculate their individual parameters.

The odo can be 100.000% accurate and the speedo out by a variey of percentaces across the range.

It is why the "Speedo Check" zone on the F4 just south of Campbelltown made no sense. Thank goodness someone realised the error and changed it to an ODO check zone! (Who would have thought there was someone in the RTA with sense!)

Originally Posted by Lotz-A-Landies

It is why the "Speedo Check" zone on the F4 just south of Campbelltown made no sense. Thank goodness someone realised the error and changed it to an ODO check zone! (Who would have thought there was someone in the RTA with sense!)

Before GPS came along, I used that stretch for a speedo check zone. If I sat on 120kph, then it should take me 30sec to cover 1km.
Not terribly accurate I know but better than nothing.

BTW, it's the F5. The F4 goes west . I think they're all called Ms now anyway.