So you have the conventional speedo and rev counter in the dash? Do you have a digital readout in between them that you can scroll through?
Changing the Clocks will be a royal PITA but do the French accept the centre readout being km? If your car supports it (2007 is a fine vintage) can you change the readout units to metric?
You will get L/km and kmh if the feature supports it but I would doubt that this will satisfy EU vehicle standards.
My other suggestion is to do the old motorcycle import trick (if it exists as mph to kmh) and get a speedo overlay http://www.clusterrepairsuk.co.uk/kmh-to-mph-dials/model/audi-a6
Good luck