The most complete site that I know:
http://www.renaultoloog.nl/
(on the left, in the menu, you can select French, German or English if you do not understand Dutch)
Only a problem: it only show one car of each, it does not always include restylings (and in some cases a picture of a restyled car is used as first model, or vice-versa).
The site that I use for chassis-code of recent models:
http://www.autoweb-france.com/index.php?rub=1&pr=Renault&all=Y
Renault in the USA:
http://www.renaultusa.org/