406.Mph to Kmh. - Quinny
On my Vectra,it was possible to change the odometer from mph to kmh, simply by holding in the reset button on the dash, and then switching the ignition on.

Is it possible to do the same on a 406 HDi?
406.Mph to Kmh. - Dynamic Dave
Don't you mean the displayed mileage rather than the speed?
406.Mph to Kmh. - Quinny
That's correct Dave.

I'm off to France today,and want the mileage to read km,rather than miles.
406.Mph to Kmh. - Chris S
If you can do mental arithmatic and drive safely then multiply the mph by 1.6 to give the corresponding kmh speed.
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Relax, it`s a Rover!
406.Mph to Kmh. - Dynamic Dave
The speedo should display both anyway, but Quinny actually wanted to convert the odometer reading from miles to kilometres.
406.Mph to Kmh. - Frogeye
Sorry but this is a bit late for Quinny. If the car has a trip computer as most Hdi's have, you can alter this to display km. You will then have both miles and km.