in this country its called clocking and ilegal-i think!
I imagine your right.If you clocked a car then kept it no one apart from the mot tester would know, but to knowingly sell a car with incorrect milage is probbably the illegal bit.Fairly silly question in the first place I cant think of any other reason to clock a motor either!?I don't think it's actually illegal until you use the new reading to try and mislead someone about how many miles the vehicle has travelled, but why else would you want to do it?
From a website that advertises a clocking service
Speedo Specialists complies fully with all applicable laws and we are a professional electronic and diagnostic technician. Whilst it is NOT an offence to alter your private vehicle speedometer / odometer in the UK, it is an offence to sell it with a lower or higher than actual reading unless you inform the buyer of the true reading.
even somwhere in europe ... a girl told me that she bought a p38 2001 and after , she found that the speedometer was reversing ... how ? due an old checkbook found on the driver seat pocket .