[donaltroddyn]

I don't think Odometers are reliable enough, especially as the basis for a tax. You'd certainly see an increase in average tyre size!

[adrianN]

They're probably accurate to within less than 10%. How many kilometers would you have to drive to save a dollar from slightly bigger tyres?

[donaltroddyn]

I was being slightly facetious in referencing tyre size, although people regularly have to adjust speedo/odometers by 10% or more when fitting large tyres on off-roaders.

Odometers can have their values changed at will, at least in ICE vehicles, often for valid reasons.

[jdashg]

Fudging do numbers illicitly is already a huge no-no in the US.

[donaltroddyn]

It also is in Ireland, but there are valid reasons, such as as replacing an ECU or dash cluster.

Unless auto manufacturers are required to fit much more secure odometers, I can't see them in their current incarnation used as the basis for a tax.

[lopmotr]

New Zealand collects road tax on diesel vehicles using odometer readings. It generally works for heavy commercial vehicles where the owners have more to lose risking fraud but I know private vehicle owners who would wind back or disconnect their odometer to avoid the tax.