Sites that I use for the "typ" info (set in the "chassis" field on the site) :
http://home.rhein-zeitung.de/~ulf.mueller/defa/misc/typen_vw.html
http://de.wikipedia.org/wiki/Volkswagen
http://www.gt2.eu/listModelsAction.do?category_id=0&application_type=1&make_id=1- 0139

Discussions about that:
http://imcdb.opencommunity.be/forum_topic-713-Precision_for_some_VW__Typ_.html