on the way back from cheesegraters, thought I'd test my new wagon's (2006 VZ commodore) speedo.

set the cruise control at 104km/hr on the speedo this is the result.




Unlike the Hyundai (speedo and odo read 3% high) the commodore odo is spot on.

doesn't it depend on how much wear you have on your tyres

Yep that is consistent with all the GPS test I have done TOM TOM & my nokia phone read the same the speedo is allwasy under how much depends on the make ect. The TomTom speed is the same as a stationary read out you drive past occasionaly

Most companys have a variation on the lower side just look in any wheels magazine test, hey beats getting done for speeding. I have to set road speed at work all the time on trucks so they comply to ADR 65 road speed governing laws.

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scarrgo said...

doesn't it depend on how much wear you have on your tyres

I'm sure it does, these tyres look fairly new, I'll do another test just before I ditch them and see, what the diff is.
But I'm sure it's easy enough to calculate, % of diameter change between new and worn out tyres.

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Mux said...

Most companys have a variation on the lower side just look in any wheels magazine test, hey beats getting done for speeding. I have to set road speed at work all the time on trucks so they comply to ADR 65 road speed governing laws.

Hey mux, how is that a truck overtaking me while I'm doing 110 has a sign on the back that says 'speed limited'. Ha, maybe it was your day off !

There are ways and means around it, many tricks around the computer to make it think it is only doing 100, also use a gt31 to confirm the speed at work . May have been my day off only work 4 on 4 off.