(15 Oct 2015, 9:07 pm)DaveyBowyer wrote Well how comes the driver of 7530 was doing 62mph when I was on the X18 a few month back and I was even sitting on the FWD seat above the nearside wheel?
By law, a speedometer must not under-read, but can over-read by 10% plus 6.25 mph.
Most car manufacturers will arrange that the speedometer over-reads (this gives the driver 'satisfaction').
In fact, variations in tyre wear (and pressures) can affect the actual figure indicated.
Of course the 'satisfaction' argument may not apply to commercial vehicles (and buses), but the law remains the same - 10% plus 6.25 mph is allowed.