Is it safe to connect them so low? I'm no expert by any means but I remember reading somewhere that the angle you attach the harness at is very important - if it's connected too low your spine could be compressed in a big impact..
Edit: Found the Schroth system, no Clio listed in the drop down menu but they may be a generic fitment? I guess if they've been designed/developed by a reputable company they must be safe..?
http://www.schrothshop.de/Tuning/Belts/QuickFit-asm%AE::11.html
Edit 2: From the Schroth site -
"Shoulder belts must run from the shoulders horizontally or down, at no more than a 20° angle". So as long as the belts run from your shoulders to the mounting points at 20° or less (from horizontal) it seems it's safe. You would have to check that yourself though because it will vary depending on the car and I guess your height.
http://www.schroth.com/installation-instructions/en/03_anchorage_locations_and_geometries.htm