A few years back Subaru got sued in the US because of the over-reading causing a reduction in length of warranty - it was a class action and compensation had to be paid to owners.

But we don't have that sue for anything culture in the UK.

I can't say this for all speedometers, but generally, the odometer bit is pretty accurate, and the speedo bit over-reads. A lot of areas have a measured mile and either your local trading standards lot, or a traffic policeman should know where it is.

Or with the conivance of a passenger, use the posts on a motorway. Not sure if they've been metricated, but some web research should find the answer.

I've recalibated a vintage speedo from the odometer, a bit fiddly but pretty simple.

Edited by SlidingPillar on 15/12/2012 at 12:55

A lot of areas have a measured mile and either your local trading standards lot, or a traffic policeman should know where it is.

Unless this dead straight then its plus or minus 10%.

There are three near where I used to live in leeds all three are inaccurate to a certain degree.

Allready mentioned.