Thread: Odometer inaccuracy

Originally Posted by DanW

Really? I've always found Google Maps to be pretty inaccurate themselves. Not just on actual road routes but on distances as well. whereis.com seems a bit better but they also seem not to be able to keep up with infrastructure changes making the actual distance different from that indicated on the website.

Google maps should be pretty accurate on established routes. For instance, it logs Perth CBD to Kalgoorlie as 594km. So does Travel Around Australia (which uses Whereis), and the WA traveller's portal list it as 596km.

Not much difference between them. So if you specify exact start and end points (eg an intersection) on established roads, I'd be confident that the distance reported would be more accurate than the average car's odometer.

I guess it depends what you're using as a reference to gauge the various GPS/mapping providers' accuracies? Short of getting a survey map and a good digital map wheel, what standard do you use to determine the accuracy of Whereis vs Google?

Cheers,

Gordon

Originally Posted by Colin Pedersen

..This explains why cursing at 119 on the Highway the radar guys wave at me...

They were trying to get you to stop cursing at 119 kph!

Originally Posted by gghaggis

There are two "hidden" screens - which one are you accessing?

Cheers,

Gordon

I am trying to access the GPS screen as discussed above.

Would good to know what the other screen is and its pin.

Originally Posted by DanW

SNIP I read "Wheels" regularly and they use "Actual speed at 100km/hr..." as a test point and nearly all of them are actually 96 or 97km/hr

Hi Dan,
That actually means that the speedo is reading high, as you would expect.

What it is saying is that for a speed of 100km/h indicated on the speedo, the actual speeds were 96 or 97km/h.

Best Wishes,
Peter

Originally Posted by gghaggis

Hi Jesse,

If you have a separate GPS unit, measure against that on a long straight level road. Or calc a travel distance using Google Maps and drive it.

Cheers,

Gordon

Will do - when I get back from the east. But I repeat - this is a WELL known highway (to me at least) - I've driven it hundreds of times in the last 40 years, and know the distance markers that I used to be pretty accurate, so don't expect much to change. However, will run this cross-check in 10 days when I return.

Also - for all those kind folk who have noted that almost all cars nowadays have speedos that read above real speeds - thanks, but my interest is in distance traveled, not speeds. And no - I'm not complaining! - it's just good to know the real situation, and I wondered if my D4 is "unique" in this behaviour.

Originally Posted by Jesse B

And no - I'm not complaining! - it's just good to know the real situation, and I wondered if my D4 is "unique" in this behaviour.

Hmm - now you've got me intrigued - I might have to try a test run myself!

Cheers,

Gordon

Originally Posted by Jesse B

..... ..... .....

I wondered if my D4 is "unique" in this behaviour.

No, my 1973 Series III LWB did the same thing. It read 100 km for 107 km actually travelled when the retreads were new and 106 km travelled when they were worn.

However that was almost certainly because I think it had the speedo from a SWB fitted, so it was calibrated for 650 or 700x16 tyres, not 750x16 and so both the speedometer and odometer were out. At an indicated 90kph, I was actually doing 100kph.

That doesn't have much to do with your situation. It just amuses me that the latest Land Rover isn't much better than my old Series III, which I always suspected was built up from odd bits, especially as when I bought it in 1983, the motor was from an early 60's Land Rover.

Originally Posted by vnx205

No, my 1973 Series III LWB did the same thing. It read 100 km for 107 km actually travelled when the retreads were new and 106 km travelled when they were worn.

However that was almost certainly because I think it had the speedo from a SWB fitted, so it was calibrated for 650 or 700x16 tyres, not 750x16 and so both the speedometer and odometer were out. At an indicated 90kph, I was actually doing 100kph.

That doesn't have much to do with your situation. It just amuses me that the latest Land Rover isn't much better than my old Series III, which I always suspected was built up from odd bits, especially as when I bought it in 1983, the motor was from an early 60's Land Rover.

In series vehicles (and others with mechanical speedo drives), the ODO reading is directly related to the speedo reading - as they are both driven by the same cable. IME 110/defender speedos under-read on standard tyres but are spot on if you fit 33's.

The D3/4/RR(?) is a different kettle of fish. As it has an inbuilt GPS(?) and a billion sensors there is not necessarily a correlation between the speedo reading and the ODO reading (though there could be?). Jesse - I assume you have standard wheels? (sorry if you have mentioned and I missed it). Maybe this is yet another software glitch???