04 1.9 Setting speedo to km/h in Scenic II - DP
In preparation for a forthcoming trip to the Continent I tried this out last night and it works a treat. Just in case this is of use to anyone (it doesn't appear to be in the handbook), I've posted it here:

To set Renault Scenic II / Grand Scenic digital speedometer and trip computer to metric:

Ignition must be off (so open and close the door in the case of full keyless models)
Press and hold the upper (^) fuel computer button on the end of the wiper stalk
Still holding the ^ button, insert the key card into the slot on the dash.
Make sure you're not touching the clutch or brake pedals.
Still holding the ^ button, press and hold the Engine Start/Stop button. The ignition will come on.
After about 5 seconds, the speedo appears, and begins to flash.
After another 5 seconds, the units switch from mph to km/h but the speedo still flashes.
After another 5 seconds, the whole thing stops flashing.
Voila - you now have km/h speedo, and the computer now reads in metric too.

To switch back to miles and gallons, repeat the same process.

Cheers
DP